fs/ocfs2/super.c: use OCFS2_MAX_VOL_LABEL_LEN and strlcpy

Replace strncpy(size 63) by defined value.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>