RDMA/uverbs: Prevent leak of reserved field

initialize to zero the response structure to prevent
the leakage of "resp.reserved" field.

drivers/infiniband/core/uverbs_cmd.c:1178 ib_uverbs_resize_cq() warn:
	check that 'resp.reserved' doesn't leak information

Fixes: 33b9b3ee ("IB: Add userspace support for resizing CQs")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -1153,7 +1153,7 @@ ssize_t ib_uverbs_resize_cq(struct ib_uverbs_file *file,
 			    int out_len)
 {
 	struct ib_uverbs_resize_cq	cmd;
-	struct ib_uverbs_resize_cq_resp	resp;
+	struct ib_uverbs_resize_cq_resp	resp = {};
 	struct ib_udata                 udata;
 	struct ib_cq			*cq;
 	int				ret = -EINVAL;