cdrom: make unregister_cdrom() return void

Now unregister_cdrom() always returns 0.
Make it return void and update all callers that check the return value.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Cc: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index c4213b7..663a7f7 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -442,7 +442,7 @@
 }
 #undef ENSURE
 
-int unregister_cdrom(struct cdrom_device_info *cdi)
+void unregister_cdrom(struct cdrom_device_info *cdi)
 {
 	cdinfo(CD_OPEN, "entering unregister_cdrom\n"); 
 
@@ -455,7 +455,6 @@
 
 	cdi->ops->n_minors--;
 	cdinfo(CD_REG_UNREG, "drive \"/dev/%s\" unregistered\n", cdi->name);
-	return 0;
 }
 
 int cdrom_get_media_event(struct cdrom_device_info *cdi,