RDMA/bnxt_re: Unconditionly fence non wire memory operations

HW requires an unconditonal fence for all non-wire memory operations
through SQ. This guarantees the completions of these memory operations.

Signed-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>