iommu/amd: Remove conditions from domain free paths

Don't use tlb as some flag to indicate if protection_domain_alloc()
completed. Have protection_domain_alloc() unwind itself in the normal
kernel style and require protection_domain_free() only be called on
successful results of protection_domain_alloc().

Also, the amd_iommu_domain_free() op is never called by the core code with
a NULL argument, so remove all the NULL tests as well.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/10-v2-831cdc4d00f3+1a315-amd_iopgtbl_jgg@nvidia.com


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