sc16is7xx: always write state when configuring GPIO as an output

The regmap_update first reads the IOState register and then triggers
a write if needed. However, GPIOS might be configured as an input so
 the read to IOState on this GPIO is the current state which might
be random.

Signed-off-by: Francois Berder <Francois.Berder@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>