drm/msm/dp: update the DP PHY and controller programming for sm8150

Update the AUX setup sequence for DP PHY on sm8150 in order to
enable AUX transactions once the cable is plugged in. Update the
values for the voltage swing and pre-emphasis levels used when
programming the DP PHY during the link power on sequence.
Furthermore, update the controller programming to ensure all
controller state transitions happens correctly.

Change-Id: I0b16ac79e9679a7aac119548a226531698400935
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>