kselftest/arm64: pac: Fix skipping of tests on systems without PAC

kselftest/arm64: pac: Fix skipping of tests on systems without PAC

[ Upstream commit 0c69bd2ca6ee20064dde7853cd749284e053a874 ]

The PAC tests check to see if the system supports the relevant PAC features
but instead of skipping the tests if they can't be executed they fail the
tests which makes things look like they're not working when they are.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210819165723.43903-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>