refactor(cpufeat): prepare FEAT_PAuth for FEATURE_DETECTION

Convert the old style is_armv8_3_pauth_present() to the new style
is_feat_pauth_{present, supported}() helpers and hook FEATURE_DETECTION
into it. This is in preparation for converting FEAT_PAuth to FEAT_STATE.

Change-Id: Iec8c3477fafb2cdae67d39ae4da2cca76a67511a
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
4 files changed