help-mtl-psm2.txt: remove stale opal_show_help() messages

These messages are not referred to in code anywhere.

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

Author: jsquyres

ompi/mca/mtl/psm2/help-mtl-psm2.txt

@@ -2,6 +2,7 @@
 #
 # Copyright (C) 2009. QLogic Corporation.  All rights reserved.
 # Copyright (c) 2013-2017 Intel, Inc. All rights reserved.
+# Copyright (c) 2022      Cisco Systems, Inc.  All rights reserved.
 # $COPYRIGHT$
 #
 # Additional copyrights may follow
@@ -13,11 +14,6 @@ Initialization of PSM2 library failed.
 
   Error: %s
 #
-[debug level]
-Unable to set PSM2 debug level.
-
-  Error: %s
-#
 [unable to open endpoint]
 PSM2 was unable to open an endpoint. Please make sure that the network link is
 active on the node and the hardware is functioning.
@@ -40,9 +36,6 @@ Unable to post application receive buffer (psm2_mq_irecv or psm2_mq_imrecv).
   Buffer:     %p
   Length:     %llu
 #
-[path query mechanism unknown]
-Unknown path record query mechanism %s. Supported mechanisms are %s.
-#
 [message too big]
 Message size %llu bigger than supported by PSM2 API. Max = %llu
 #