ASoC: Put WM8962 GPIO2/3 into GPIO mode when configuring platform data too

GPIO2 and GPIO3 on the WM8962 are MFPs and need to be put into GPIO mode
before the GPIO block can be used to control them. We're already doing
this when used via gpiolib, factor out the code for use when setting static
configurations via platform data as well.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>