ASoC: rouleur-mbhc: Fix aux cable detected as unsupported sometimes

Aux cable is detected as unsupported sometimes due to it being
detected as cross conn. Increase hph cross conn threshold to 350mV
so that it detects fine.

Change-Id: I87e4bd36f80d7cd62e06c76acf9c9d06bb6f148a
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>