gpiolib: wm8994: Pay attention to the value set when enabling as output

Not paying attention to the value being set is a bad thing because it
means that we'll not set the hardware up to reflect what was requested.
Not setting the hardware up to reflect what was requested means that the
caller won't get the results they wanted.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>