ARM: dts: msm: Add dmic clock rate on ECPP path for 8996

DMIC clock on ECPP(Echo cancellation Ping-Pong) path can
run at 1.2MHz. Change configures DMIC clock rate for ECPP
path in codec device node.

CRs-fixed: 1022917
Change-Id: Ie7a0a5c57af608cdb42fac9f0f95fe427de8ea1d
Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>
Signed-off-by: Vidyakumar Athota <vathota@codeaurora.org>