drm/amd/display: update odm mode validation to be in line with policy

Previously 8k30 worked with dsc and odm combine due to a workaround that ran
the formula a second time with dsc support enable should dsc validation fail.
This worked when clocks were low enough for formula to enable odm to lower
voltage, however now broke due to increased clocks.

This change updates the ODM combine policy within the formula to properly
reflect our current policy within DC, only enabling ODM when we have to, as
well as adding a check for viewport width when dsc is enabled.

As a side effect the redundant call to dml when odm is required is now
unnecessary.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>