power: smb5-lib: Increase OV threshold on ADC USB_IN_V reading

Update USB_IN channel read sequence. This channel read sequence is
done to prevent over voltage in charger.

As part of the read sequence, Increase 12V OV threshold to 14.6V
before and restore to 13.2V after ADC USB_IN_V channel reading.

Change-Id: I1d1e6f50fb1992447f5919661128e75967918896
Signed-off-by: Harry Yang <harryy@codeaurora.org>