[rhythmbox] fmradio: Fix build with GStreamer master

[Bastien Nocera <hadess src gnome org>]

commit b182c6b9e1d09e601bac0b703cc5f8b159ebbc3a
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Oct 9 13:11:47 2017 +0200

    fmradio: Fix build with GStreamer master
    
    The plugin description is not supposed to be a string constant, but an
    unescaped string, to be concatenated with function names.
    
    This used to be acceptable (though would have warned), but breaks with
    the GStreamer 1.13 development branch.
    
    rb-fm-radio-gst-src.c:181:6: error: pasting ""rbsilencesrc"" and "_get_desc" does not give a valid 
preprocessing token
          "rbsilencesrc",
          ^
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788706

 plugins/fmradio/rb-fm-radio-gst-src.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plugins/fmradio/rb-fm-radio-gst-src.c b/plugins/fmradio/rb-fm-radio-gst-src.c
index 09d709c..88abdaf 100644
--- a/plugins/fmradio/rb-fm-radio-gst-src.c
+++ b/plugins/fmradio/rb-fm-radio-gst-src.c
@@ -178,7 +178,7 @@ plugin_init (GstPlugin *plugin)
 
 GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
                   GST_VERSION_MINOR,
-                  "rbsilencesrc",
+                  rbsilencesrc,
                   "element to output silence",
                   plugin_init,
                   VERSION,