iommu/vt-d: Add missing "__init" for rmrr_sanity_check()

rmrr_sanity_check() calls arch_rmrr_sanity_check(), which is marked as
"__init". Add the annotation for rmrr_sanity_check() too. This function is
currently only called from dmar_parse_one_rmrr() which is also "__init".

Signed-off-by: Marco Bonelli <marco@mebeim.net>
Link: https://lore.kernel.org/r/20220210023141.9208-1-marco@mebeim.net
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20220301020159.633356-11-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>