ASoC: wm5102: Correct micbias DAPM supplies

ARIZONA_MICB1_ENA_SHIFT was used for micbias 2 and 3. This change
correctly uses the ARIZONA_MICBX_ENA_SHIFT for each corresponding DAPM
supply. This should not have caused any problems as the micbias enables
are in the same place in each register.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>