ASoC: Fix vaud18 power leakage of mt6359

ASoC: Fix vaud18 power leakage of mt6359

vaud18 is power of mt6359 audio path. It
should only enable when audio is used,
instead of in boot up stage.
Once mt6359 audio path is enabled or disabled,
vaud18 is controlled by regulator supply widget
"LDO_VAUD18". Due to vaud18 is controlled by
regulator dapm macro instead of regmap, the macro
MT6359_LDO_VAUD18_CON0 and variable avdd_reg
is no used and removed from mt6359.h.

Signed-off-by: Shane.Chien <shane.chien@mediatek.com>
Link: https://lore.kernel.org/r/1604975492-6142-2-git-send-email-shane.chien@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>