ASoC: wm8974: Correct boost mixer inputs

Bit 6 of INPPGA (INPPGAMUTE) does not control the Aux path, it controls
the input PGA path, as can been seen from Figure 8 Input Boost Stage in
the datasheet. Update the naming of things in the driver to match this
and update the routing to also reflect this.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20231113155916.1741027-1-ckeepax@opensource.cirrus.com


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