drm/amd/display: Revert "dc: Keep VBios pixel rate div setting util next mode set"

This reverts commit 4d4d3ff1 ("drm/amd/display: Keep VBios pixel rate div
setting util next mode set") which causes issue.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Webb Chen <yi-lchen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>