ARM: dts: msm: update dmic clock rate to avoid issue in msm8937

In 8937 with wcd9326, when testing on mockup handset
observed 4.8MHz clock rate resulting in noise issue and swap
in DMICs. Reduce the clock rate to 2.4MHz to avoid these issues.

Change-Id: I92269c18289200fbbf209ecbe4388f29f652e406
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>