disp: msm: dsi: Update dsi byte interface clock calculation

Update dsi byte interface clock as per hardware recommendation.
For Phy ver 2.0 and below: byte intf clk equals to byte clk.
For Phy ver 3.0 and above: byte intf clk equals to byte clk / 2.

Change-Id: Ic3af2e4348403aeacb2e1c73c4dc133db63a51a4
Signed-off-by: Ritesh Kumar <riteshk@codeaurora.org>
Signed-off-by: Lipsa Rout <lrout@codeaurora.org>