drm/msm/dsi_pll_7nm: restore VCO rate during restore_state

PHY disable/enable resets PLL registers to default values. Thus in
addition to restoring several registers we also need to restore VCO rate
settings.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Fixes: 1ef7c99d ("drm/msm/dsi: add support for 7nm DSI PHY/PLL")
Signed-off-by: Rob Clark <robdclark@chromium.org>