iommu/amd: Introduce generic function to set multibit feature value

Define generic function `iommu_feature_set()` to set the values
in the feature control register and replace `iommu_set_inv_tlb_timeout()`
with it.

Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20250307095822.2274-2-sarunkod@amd.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>