drm/msm/dsi: configure VCO rate for 10nm PLL driver

[ Upstream commit 8531f0587f5c9e1a74cd9543a97617349f5e0706 ]

Currenty the VCO rate in the 10nm PLL driver relies
on the parent rate which is not configured.

Configure the VCO rate to 19.2 Mhz as required by
the 10nm PLL driver.

Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>