hwtracing: coresight: 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.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250703183534.2075569-1-robh@kernel.org