iommu/amd: Propagate errors from amd_iommu_init_api

This function can fail. Propagate any errors back to the
initialization state machine.

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

diff --cc drivers/iommu/amd_iommu.c
Simple merge

diff --cc drivers/iommu/amd_iommu_init.c
Simple merge

diff --cc drivers/iommu/amd_iommu_proto.h
Simple merge