iommu/arm-smmu-v3: cleanup arm_smmu_dev_{enable,disable}_feature

Fold the arm_smmu_dev_has_feature arm_smmu_dev_feature_enabled into
the main methods.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220708080616.238833-5-hch@lst.de
Signed-off-by: Joerg Roedel <jroedel@suse.de>