regulator: Default GPIO controlled WM8994 regulators to disabled

This ensures that if the GPIO was not enabled prior to the driver
starting the regulator API will insert the required powerup ramp
delay when it enables the regulator.  The gpiolib API does not
provide this information.

[Rewrote changelog to describe the actual change -- broonie.]

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>