make cdrom.c:check_for_audio_disc() static

This patch makes the needlessly global check_for_audio_disc() static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/cdrom/cdrom.c

@@ -1152,7 +1152,7 @@ int open_for_data(struct cdrom_device_info * cdi)
 /* This code is similar to that in open_for_data. The routine is called
    whenever an audio play operation is requested.
 */
-int check_for_audio_disc(struct cdrom_device_info * cdi,
+static int check_for_audio_disc(struct cdrom_device_info * cdi,
 				struct cdrom_device_ops * cdo)
 {
         int ret;