drm/vmwgfx: fix kernel-doc warnings in vmwgfx_drv.h

drm/vmwgfx: fix kernel-doc warnings in vmwgfx_drv.h

Fix 45+ kernel-doc warnings in vmwgfx_drv.h:
- spell a struct name correctly
- don't have structs between kernel-doc and its struct
- end description of struct members with ':'
- start all kernel-doc lines with " *"
- mark private struct member and enum value with "private:"
- add kernel-doc for enum vmw_dma_map_mode
- add missing struct member comments
- add missing function parameter comments
- convert "/**" to "/*" for non-kernel-doc comments
- add missing "Returns:" comments for several functions
- correct a function parameter name

to eliminate kernel-doc warnings (examples):

Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:128 struct vmw_bo; error:
 Cannot parse struct or union!
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:151 struct member 'used_prio'
 not described in 'vmw_resource'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:151 struct member 'mob_node'
 not described in 'vmw_resource'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:199 bad line: SM4 device.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:270 struct member 'private'
 not described in 'vmw_res_cache_entry'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:280 Enum value
 'vmw_dma_alloc_coherent' not described in enum 'vmw_dma_map_mode'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:280 Enum value
 'vmw_dma_map_bind' not described in enum 'vmw_dma_map_mode'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:295 struct member 'addrs'
 not described in 'vmw_sg_table'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:295 struct member 'mode'
 not described in 'vmw_sg_table'
vmwgfx_drv.h:309: warning: Excess struct member 'num_regions' description
 in 'vmw_sg_table'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:402 struct member 'filp'
 not described in 'vmw_sw_context'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:732 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:742 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:762 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:887 No description found for
 return value of 'vmw_fifo_caps'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:901 No description found for
 return value of 'vmw_is_cursor_bypass3_enabled'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:906 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:961 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:996 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1082 cannot understand
 function prototype: 'const struct dma_buf_ops vmw_prime_dmabuf_ops;'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1303 struct member 'do_cpy'
 not described in 'vmw_diff_cpy'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1385 function parameter 'fmt'
 not described in 'VMW_DEBUG_KMS'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1389 This comment starts with
 '/**', but isn't a kernel-doc comment.
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1426 function parameter 'vmw'
 not described in 'vmw_fifo_mem_read'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1426 No description found for
 return value of 'vmw_fifo_mem_read'
Warning: drivers/gpu/drm/vmwgfx/vmwgfx_drv.h:1441 function parameter
 'fifo_reg' not described in 'vmw_fifo_mem_write'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patch.msgid.link/20260219215548.470810-1-rdunlap@infradead.org