ASoC: wcd9xxx: Fix incorrect register write sequence

The logic to write a value to mbhc scaling mux register
first and then update a bit got reversed. This update of
bit is codec specific and should be done after the common
register write else it will get overwritten.

Change-Id: I21ccb88ef69b96420b9e8a671b8e97202eefb47f
Signed-off-by: Simmi Pateriya <simmip@codeaurora.org>