xilinx: r5: Include the sys_r5_proto.h header for future use

xilinx: r5: Include the sys_r5_proto.h header for future use

Currently when using "W=1" with xilinx_zynqmp_r5_defconfig, getting
below warnings.
cc1.real: warning: ./arch/arm/mach-zynqmp-r5/include:
		No such file or directory [-Wmissing-include-dirs]
Fix W=1 missing-include-dirs warnings by including the headers and
sys_r5_proto.h file which can be used.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Link: https://lore.kernel.org/r/20240111030029.2565827-1-venkatesh.abbarapu@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>