ASoC: sgtl5000: Fix warning due to the lack of REGULATOR_CHANGE_VOLTAGE

Fix the following warning during kernel boot:

0-000a: 850 <--> 1600 mV at 1200 mV normal
0-000a: Voltage range but no REGULATOR_CHANGE_VOLTAGE

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>