iommu/vt-d: Remove the CONFIG_X86 wrapping from iommu init hook

iommu/vt-d: Remove the CONFIG_X86 wrapping from iommu init hook

iommu init hook is wrapped in CONFI_X86 and is a remnant of dmar.c when
it was a common code in "drivers/pci/dmar.c". This was added in commit
(9d5ce73a64be2 x86: intel-iommu: Convert detect_intel_iommu to use
iommu_init hook)

Now this is built only for x86. This config wrap could be removed.

Signed-off-by: Vineeth Pillai (Google) <vineeth@bitbyteword.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20250616131740.3499289-1-vineeth@bitbyteword.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20250714045028.958850-2-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>