drm/amd/display: Add DSC padding for OVT Support

drm/amd/display: Add DSC padding for OVT Support

[Why]
-Certain OVT timings require DSC configurations which divide the
horizontal active unevenly across DSC slices
-DSC slices must be even, so padding needs to be added to the active
to make this possible
-The pixel clock of the HW now needs to be increased to accommodate
the extra padded pixels
-To keep the line time the same, the blank of the HW timing needs to
be increased as well

[How]
-Calculate h_active padding, h_total padding, and pixel clock based
off of the original OVT timing and DSC calculations
-Store these values in the pipe and program HW with these modifications
-Added general support for cases where DSC slice config does not evenly
split the horizontal active by fixing some slice width calculations
-Updated PPS calculations for these cases

Reviewed-by: Chris Park <chris.park@amd.com>
Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Relja Vojvodic <rvojvodi@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>