ARM: dts: msm: put rot_clk at lowest voltage corner for sm8150

Rotator_clk is enabled by display driver to ensure the rotator hw
is clocked to run the power collapse and enable sequence. By setting
it to lowest voltage corner this change will save power.

Change-Id: I8cb83ae1cda0bf34edd1eb5b78e2277142773de5
Signed-off-by: Abhijit Kulkarni <kabhijit@codeaurora.org>