kselftest/arm64: add pmull feature to hwcap test

Add the pmull feature check in the set of hwcap tests.

Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230815040915.3966955-4-zengheng4@huawei.com


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