serial: xilinx_uartps: read reg size from DTS

serial: xilinx_uartps: read reg size from DTS

Current implementation uses `CDNS_UART_REGISTER_SPACE(0x1000)`
for request_mem_region() and ioremap() in cdns_uart_request_port() API.

The cadence/xilinx IP has register space defined from offset 0x0 to 0x48.
It also mentions that the register map is defined as [6:0]. So, the upper
region may/maynot be used based on the IP integration.

In Axiado AX3000 SoC two UART instances are defined
0x100 apart. That is creating issue in some other instance due to overlap
with addresses.

Since, this address space is already being defined in the
devicetree, use the same when requesting the register space.

Fixes: 1f7055779001 ("arm64: dts: axiado: Add initial support for AX3000 SoC and eval board")
Acked-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Harshit Shah <hshah@axiado.com>
Link: https://lore.kernel.org/r/20250902-xilinx-uartps-reg-size-v3-1-d11cfa7258e3@axiado.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>