chipidea's ffs_nr() is pretty much what __ffs() does.

Use that one instead.
Signed-off-by: NFelipe Balbi <balbi@ti.com>
[rebased on top of debug infrastructure rework]
Signed-off-by: NAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>