Add a new DT property, nxp,inverted-out, to invert the polarity
of the output.

Tested on PCA9634.
Signed-off-by: NAnders Darander <anders@chargestorm.se>
Acked-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NJacek Anaszewski <jacek.anaszewski@gmail.com>