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/Documentation/cdrom/cdrom-standard.tex b/Documentation/cdrom/cdrom-standard.tex
index c713aeb..c06233f 100644
--- a/Documentation/cdrom/cdrom-standard.tex
+++ b/Documentation/cdrom/cdrom-standard.tex
@@ -777,7 +777,7 @@
 it may have as many structures $<device>_info$ as there are minor devices
 active. $Register_cdrom()$ builds a linked list from these. 
 
-\subsection{$Int\ unregister_cdrom(struct\ cdrom_device_info * cdi)$}
+\subsection{$Void\ unregister_cdrom(struct\ cdrom_device_info * cdi)$}
 
 Unregistering device $cdi$ with minor number $MINOR(cdi\to dev)$ removes
 the minor device from the list. If it was the last registered minor for