Revert "drm/amd/display: reallocate DET for dual displays with high pixel rate ratio"

Revert commit 5f3401ee ("drm/amd/display: reallocate DET for dual displays with high pixel rate ratio")

[Why]
Previously had modified DET allocation algorithm to allocate less DET
segments for lower pixel rate display and more DET segments for higher
pixel rate display.  But noticed it is causing underflow when higher
pixel rate display is not displaying at higher mode

[How]
Roll back change

Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Samson Tam <samson.tam@amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>