ARM: dts: msm: Modify byte clk and pixel clk sources for sdm845

Modify byte clock and pixel clock source for DSI in SDM845.
Earlier the clocks were referencing to disp_cc clocks.

Change-Id: I883e499049ff50d9fbb017c7cc571fb0d8d11dfe
Signed-off-by: Shashank Babu Chinta Venkata <sbchin@codeaurora.org>