btl/openib: fix a problem with ib query

Under certain circumstances, ibv_exp_query_device was
returning an error due to uninitialized fields in the
extended attributes struct.

Fixes: #5810
Fixes: #5914

Signed-off-by: Howard Pritchard <howardp@lanl.gov>
(cherry picked from commit 8126779a354b3e0c720d3e1790f7b936dd5b93b2)

opal/mca/btl/openib/btl_openib_component.c

@@ -1692,6 +1692,7 @@ static int init_one_device(opal_list_t *btl_list, struct ibv_device* ib_dev)
         goto error;
     }
 #if HAVE_DECL_IBV_EXP_QUERY_DEVICE
+    memset(&device->ib_exp_dev_attr, 0, sizeof(device->ib_exp_dev_attr));
     device->ib_exp_dev_attr.comp_mask = IBV_EXP_DEVICE_ATTR_RESERVED - 1;
     if(ibv_exp_query_device(device->ib_dev_context, &device->ib_exp_dev_attr)){
         BTL_ERROR(("error obtaining device attributes for %s errno says %s",