arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early

arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early

commit edf298cfce47 upstream.
Alex Shi rewrite this commit on func this_cpu_has_cap(). The following commit
log is still meaningful.

    this_cpu_has_cap() tests caps->desc not caps->matches, so it stops
    walking the list when it finds a 'silent' feature, instead of
    walking to the end of the list.

    Prior to v4.6's 644c2ae198412 ("arm64: cpufeature: Test 'matches' pointer
    to find the end of the list") we always tested desc to find the end of
    a capability list. This was changed for dubious things like PAN_NOT_UAO.
    v4.7's e3661b128e53e ("arm64: Allow a capability to be checked on
    single CPU") added this_cpu_has_cap() using the old desc style test.

    CC: Suzuki K Poulose <suzuki.poulose@arm.com>
    Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    Acked-by: Marc Zyngier <marc.zyngier@arm.com>
    Signed-off-by: James Morse <james.morse@arm.com>
    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alex Shi <alex.shi@linaro.org>