[PATCH] fix cdrom open

Some time ago the cdrom open routine was changed so that we call the
driver's open routine before checking to see if it is read only.  However,
if we discovered that a read write open was not possible and the open
flags required a writable open, we just returned -EROFS without calling
the driver's release routine.   This seems to work for most cdrom drivers,
but breaks the Powerpc iSeries virtual cdrom rather badly.

This just inserts the release call in the error path to balance the call
to "->open()" done by "open_for_data()".

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>