ASoC: wcd938x: Enable digital clk for tx0 if micbias enabled

Mute is observed in amic record sometimes in concurrency with
sva. This is because if record is over tx0 then digital clk
is not enabled. Enable clk after enabling micbias to resolve mute.

Change-Id: Iba3aa4fade0ac5889218eaee2c5d2c4bd4431d50
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>