FROMLIST: drm/msm/dsi/phy: rework register setting for 7nm PHY

In preparation to adding the sm8350 and sm8450 PHYs support, rearrange
register values calculations in dsi_7nm_phy_enable(). This change bears
no functional changes itself, it is merely a preparation for the next
patch.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20221207012231.112059-6-dmitry.baryshkov@linaro.org