ASoC: msm8x16: add master clock frequency property.

8916 ULT audio core can support 9.6 and 12.28 MHz master frequency
and the frequencies can be used differently when internal codec only
or internal codec with external PA.

Add mclk frequency property in dtsi to inform machine driver to
configure master clock based on the value sent from the dtsi.

CRs-Fixed: 662773
Change-Id: I30880e13593477fe7f0c1211907ba6f3a1e2cd36
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>