linux-phytec-ti

arm64: Handle width of a cpuid feature

Introduce a helper to extract cpuid feature for any given
width.

Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Tested-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>