drm/amd/display: Add DSC delay factor workaround

[Why]
Certain 4K high refresh rate modes requiring DSC are exhibiting top
of screen underflow corruption. Increasing the DSC delay by a factor
of 6 percent stops the underflow for most use cases.

[How]
Multiply DSC delay requirement in DML by a factor.
Add debug option to make this DSC delay factor configurable.

Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>