cdrom: Remove unnecessary check_for_audio_disc prototype

The actual static is defined below it but not used until later.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/cdrom/cdrom.c

@@ -337,8 +337,6 @@ do {							\
 #define CDROM_DEF_TIMEOUT	(7 * HZ)
 
 /* Not-exported routines. */
-static int check_for_audio_disc(struct cdrom_device_info * cdi,
-			 struct cdrom_device_ops * cdo);
 static void sanitize_format(union cdrom_addr *addr, 
 		u_char * curr, u_char requested);
 static int mmc_ioctl(struct cdrom_device_info *cdi, unsigned int cmd,