[easytag] Fix -Wwrite-strings warning in channel_mode_name()

[David King <davidk src gnome org>]

commit 806b8692e615b79accec39cae2154aa2fb770cd2
Author: David King <amigadave amigadave com>
Date:   Sat Sep 6 21:47:31 2014 +0100

    Fix -Wwrite-strings warning in channel_mode_name()

 src/tags/mpeg_header.c |   22 +++++++---------------
 1 files changed, 7 insertions(+), 15 deletions(-)
---
diff --git a/src/tags/mpeg_header.c b/src/tags/mpeg_header.c
index 30d8231..cb31e9a 100644
--- a/src/tags/mpeg_header.c
+++ b/src/tags/mpeg_header.c
@@ -44,30 +44,22 @@ static const gchar *layer_names[3] =
     "III"   /* Layer 3 */
 };
 
-
-
-/**************
- * Prototypes *
- **************/
-static gchar* channel_mode_name(int mode);
-
-
-
-/*************
- * Functions *
- *************/
-
-static gchar* channel_mode_name(int mode)
+static const gchar *
+channel_mode_name (int mode)
 {
-    static const gchar *channel_mode[] =
+    static const gchar * const channel_mode[] =
     {
         N_("Stereo"),
         N_("Joint stereo"),
         N_("Dual channel"),
         N_("Single channel")
     };
+
     if (mode < 0 || mode > 3)
+    {
         return "";
+    }
+
     return _(channel_mode[mode]);
 }