fs/ufs: recognize Solaris-specific file system state

Recent releases of Solaris set the fs_clean state of an unmounted UFS file
system as FSLOG ("logging fs").  However, the Linux kernel currently does
not recognize the value which represents this state.  Thus, attempting to
mount such a file system rw produces the message

kernel: ufs_read_super: can't grok fs_clean 0xfffffffd

and the file system is mounted read-only.  This patch makes the kernel
recognize that value.

Signed-off-by: Alex Viskovatoff <viskovatoff@imap.cc>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>