arm64: Add defines for APM ARMv8 implementation

This patch adds defines for APM CPU implementer ID and APM CPU part numbers in asm/cputype.h

Signed-off-by: Kumar Sankaran <ksankaran@apm.com>
Signed-off-by: Loc Ho <lho@apm.com>
Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>