Fix description of bgp speaker set arg

The name argument for bgp speaker set defines the new name for the speaker,
make the description more clear about this.

Change-Id: I29a0c87214c3c60084d0541f8b9a7abc72ff987f

neutronclient/osc/v2/dynamic_routing/bgp_speaker.py

@@ -285,7 +285,7 @@ class SetBgpSpeaker(command.Command):
         )
         parser.add_argument(
             '--name',
-            help=_("Name of the BGP speaker to update"))
+            help=_("New name for the BGP speaker"))
         add_common_arguments(parser)
         return parser