ASoC: wcd9335: Adjust DMIC clock based on sample rate

Currently DMIC clock is set at 4.8MHz for all sampling rates. For
optimal power, sampling rates <=48KHz should be set to 2.4MHz.

CRs-fixed: 971183
Change-Id: If3076f017d476cfb57fa22b75cc74ed615c8882e
Signed-off-by: Stephen Oglesby <soglesby@codeaurora.org>
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>