drm/msm/dp: update sink voltage and pre-emphasis

Update sink voltage and pre-emphasis for electrical
compliance use cases. This will ensure that the sink
and the source have the same values as requested for
each test.

CRs-Fixed: 2355015
Change-Id: Ibe045df26127c6f6d84289f28e2c70beda174f9a
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>