Add inherit mode to audio port gain config

The mode is required to correctly change the volume at the audio control
HAL v7 and above, as newer versions have an optional gain which will be
skipped if the mode is not correctly set.

Bug: 340540043
Test: m -j, manual audio test
Change-Id: I2a435807921eebd3c4a3e409b460ea854b590172
1 file changed