ALSA: ASoC: Correct inverted Mic PGA Switch control in wm8510 driver

Mic PGA Switch should be inverted in the WM8510 driver but isn't.

Reported-by:  <ext-jukka.hynninen@vaisala.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>