IB: remove support for phys MRs

We have stopped using phys MRs in the kernel a while ago, so let's
remove all the cruft used to implement them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> [core]
Reviewed-By: Devesh Sharma<devesh.sharma@avagotech.com> [ocrdma]
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>