Fix havoc wrought by commit 56f621c7f6 --
au_ffs() and ffs() are equivalent, that patch should have just replaced one
with another. Now replace ffs() with __ffs() which returns an unbiased bit
number.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>