iommu/amd: Remove redundant check

smatch static checker warning:
  drivers/iommu/amd/init.c:1989 amd_iommu_init_pci()
  warn: duplicate check 'ret' (previous on line 1978)

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 06687a03

 ("iommu/amd: Improve error handling for amd_iommu_init_pci")
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20220314070226.40641-1-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>