[PATCH] pktcdvd: Allow non-writable media to be mounted

If opening for write fails, the open method should return -EROFS.  This makes
"mount" try again with a read-only mount, instead of just giving up.

Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>