ofi common: add "usnic" to the exclude list

We never want to use usnic devices with the OFI MTL or OFI BTL (we
have the usnic BTL, instead).  So add "usnic" to the default common
OFI exclude list so that neither "usnic" nor "usnic;ofi_rxd" will be
used by the OFI MTL.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

Author: jsquyres

opal/mca/common/ofi/common_ofi.c

@@ -4,7 +4,7 @@
  *                         reserved.
  * Copyright (c) 2020-2021 Triad National Security, LLC. All rights
  *                         reserved.
- * Copyright (c) 2020      Cisco Systems, Inc.  All rights reserved
+ * Copyright (c) 2020-2021 Cisco Systems, Inc.  All rights reserved
  * Copyright (c) 2021      Nanook Consulting.  All rights reserved.
  * $COPYRIGHT$
  *
@@ -31,7 +31,7 @@ OPAL_DECLSPEC opal_common_ofi_module_t opal_common_ofi = {.prov_include = NULL,
                                                           .registered = 0,
                                                           .verbose = 0};
 
-static const char default_prov_exclude_list[] = "shm,sockets,tcp,udp,rstream";
+static const char default_prov_exclude_list[] = "shm,sockets,tcp,udp,rstream,usnic";
 static opal_mutex_t opal_common_ofi_mutex = OPAL_MUTEX_STATIC_INIT;
 
 OPAL_DECLSPEC int opal_common_ofi_is_in_list(char **list, char *item)