drivers/infiniband/core/verbs.c: fix build with gcc-4.4.4

gcc-4.4.4 has issues with initialization of anonymous unions.

drivers/infiniband/core/verbs.c: In function '__ib_drain_sq':
drivers/infiniband/core/verbs.c:2204: error: unknown field 'wr_cqe' specified in initializer
drivers/infiniband/core/verbs.c:2204: warning: initialization makes integer from pointer without a cast

Work around this.

Fixes: a1ae7d03 ("RDMA/core: Avoid that ib_drain_qp() triggers an out-of-bounds stack access")
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Steve Wise <swise@opengridcomputing.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>