arm64: kernel: Add cpuid_feature_extract_field() for 4bit sign extension
arm64: kernel: Add cpuid_feature_extract_field() for 4bit sign extension

Based on arch/arm/include/asm/cputype.h, this function does the
shifting and sign extension necessary when accessing cpu feature fields.

Signed-off-by: James Morse <ebe5c4842edd72edc3a105fa34a4e41fed7a97bc@arm.com>
Suggested-by: Russell King <ba324ca7b1c77fc20bb970d5aff6eea9377918a5@arm.linux.org.uk>
Acked-by: Catalin Marinas <15ce75b290ebaf27c3f9fd73ab848685ed3d8261@arm.com>
Signed-off-by: Will Deacon <b913f13ef92ac157955c954ccaaff7be065faba4@arm.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs