arm64/cpufeature: Use helper for ECV CNTPOFF cpufeature

The newly added support for ECV CNTPOFF open codes the recently added
helper ARM64_CPUID_FIELDS(), make use of the helper.  No functional
change.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20230523-arm64-ecv-helper-v1-1-506dfb5fb199@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/cpufeature.c

@@ -2235,11 +2235,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.capability = ARM64_HAS_ECV_CNTPOFF,
 		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
 		.matches = has_cpuid_feature,
-		.sys_reg = SYS_ID_AA64MMFR0_EL1,
-		.field_pos = ID_AA64MMFR0_EL1_ECV_SHIFT,
-		.field_width = 4,
-		.sign = FTR_UNSIGNED,
-		.min_field_value = ID_AA64MMFR0_EL1_ECV_CNTPOFF,
+		ARM64_CPUID_FIELDS(ID_AA64MMFR0_EL1, ECV, CNTPOFF)
 	},
 #ifdef CONFIG_ARM64_PAN
 	{