staging/rdma/hfi1: Detect SDMA transmission error early

It is possible for an SDMA transmission error to happen
during the processing of an user SDMA transfer. In that
case it is better to detect it early and abort any further
attempts to send more packets.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>