RDMA/irdma: Prevent rereg_mr for non-mem regions

RDMA/irdma: Prevent rereg_mr for non-mem regions

When a QP/CQ/SRQ is created, a two step process is used
where the buffer is allocated in userspace and explicitly
registered with the normal reg_mr mechanism prior to creating
the actual QP/CQ/SRQ object.

These special registrations are indicated via an ABI field
so the driver knows that they do not have a valid mkey and
to skip the actual CQP command submission.

Since these are real MR objects from the core's perspective,
it is possible for a user application to invoke rereg_mr on them
and cause a real CQP op to be emitted with the zero-initialized
mkey value of 0.

Fix this by preventing rereg_mr on these special regions.

Fixes: 5ac388db27c4 ("RDMA/irdma: Add support to re-register a memory region")
Signed-off-by: Jacob Moroni <jmoroni@google.com>
Reviewed-by: David Hu <xuehaohu@google.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>