ASoC: wcd9320: Close MICB 4 leakage path

There is leakage from MICB 4 to CDC_IN_MBHC which has a weak pull up.
Therefore there is a possibility of having false interrupt when LDO is on.
Close this leakage path by pulling up micbias 4 to VDDIO to prevent false
IRQ.

Change-Id: Ia5cbe7b7801a302aeb1ccd88406094577c838442
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>