drm/msm/dsi: Use division result from div_u64_rem in 7nm and 14nm PLL

drm/msm/dsi: Use division result from div_u64_rem in 7nm and 14nm PLL

div_u64_rem provides the result of the division and additionally the
remainder; don't use this function to solely calculate the remainder
while calculating the division again with div_u64.

A similar improvement was applied earlier to the 10nm pll in
5c191fef4ce2 ("drm/msm/dsi_pll_10nm: Fix dividing the same numbers
twice").

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-By: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20211011201642.167700-1-marijn.suijten@somainline.org
Signed-off-by: Rob Clark <robdclark@chromium.org>