kselftest/arm64: Add SVE 2.1 to hwcap test

Add coverage for FEAT_SVE2p1.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20221017152520.1039165-7-broonie@kernel.org


Signed-off-by: Will Deacon <will@kernel.org>