ubifs: Convert ubifs to use the new mount API

ubifs: Convert ubifs to use the new mount API

Convert the ubifs filesystem to the new internal mount API as the old
one will be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.

[sandeen: forward-port old patch, use dedicated context struct]]

Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Link: https://lore.kernel.org/r/20241002165834.868046-1-sandeen@redhat.com
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
cc: Richard Weinberger <richard@nod.at>
cc: Zhihao Cheng <chengzhihao1@huawei.com>
cc: linux-mtd@lists.infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>