misc: fastrpc: Use of_reserved_mem_region_to_resource() for "memory-region"

misc: fastrpc: Use of_reserved_mem_region_to_resource() for "memory-region"

Use the newly added of_reserved_mem_region_to_resource() function to
handle "memory-region" properties.

The error handling is a bit different. "memory-region" is optional, so
failed lookup is not an error. But then an error in
of_reserved_mem_lookup() is treated as an error. However, that
distinction is not really important. Either the region is available
and usable or it is not. So now, it is just
of_reserved_mem_region_to_resource() which is checked for an error.

Signed-off-by: "Rob Herring (Arm)" <robh@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Srinivas Kandagatla <srini@kernel.org>
Link: https://lore.kernel.org/r/20250703183455.2074215-1-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>