RDMA/rxe: For invalidate compare according to set keys in mr

RDMA/rxe: For invalidate compare according to set keys in mr

The 'rkey' input can be an lkey or rkey, and in rxe the lkey or rkey have
the same value, including the variant bits.

So, if mr->rkey is set, compare the invalidate key with it, otherwise
compare with the mr->lkey.

Since we already did a lookup on the non-varient bits to get this far, the
check's only purpose is to confirm that the wqe has the correct variant
bits.

Fixes: 001345339f4c ("RDMA/rxe: Separate HW and SW l/rkeys")
Link: https://lore.kernel.org/r/20220707073006.328737-1-haris.phnx@gmail.com
Signed-off-by: Md Haris Iqbal <haris.phnx@gmail.com>
Reviewed-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>