ASoC: sgtl5000: Fix VDDA and VDDIO comparison

Comparing the voltage of VDDA and VDDIO to determine whether or not to
enable VDDC manual override is insufficient. This is a problem in case
the VDDA is supplied from different regulator than VDDIO, while both
report the same voltage to the regulator framework. In that case where
VDDA and VDDIO is supplied by different regulators, the VDDC manual
override must not be applied.

Fixes: b6319b06 ("ASoC: sgtl5000: Fix charge pump source assignment")
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Igor Opaniuk <igor.opaniuk@toradex.com>
Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Link: https://lore.kernel.org/r/20191220164450.1395038-2-marex@denx.de


Signed-off-by: Mark Brown <broonie@kernel.org>