commit 5404ac8e ("isofs: cleanup mount
option processing") missed conversion of joliet option flag resulting
in non-working Joliet support.

CC: walt <w41ter@gmail.com>
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>