drm/amd/display: Apply ODM 2:1 policy for single display configuration

drm/amd/display: Apply ODM 2:1 policy for single display configuration

[Why]
Most of the time, a single display uses the ODM combine. When using
multi-display, we use ODM combine only if it is necessary. These cases
are not flexible enough for us, and we can improve them to take
advantage of our hardware. We want to have more control over the ODM
policy.

[How]
This commit add a new debug flag named
enable_single_display_2to1_odm_policy to control the ODM policy and
another flag named enable_dp_dig_pixel_rate_div_policy to fine control
the ODM combine. This is possible by adding a new "pipe.dest" parameter
that can be set to ODM 2:1 combined if we use a single display. For
dynamic ODM combine, when using DP-DIG, DCN applies K2=2 settings for
ODM combine. Note that this feature affects the following registers:

- timing.pix_clk_100khz -> DP_VID_M, DP_VID_N
- requested_pix_clk_100hz -> DP_DTOn_PHASE
- OTGn_PIXEL_RATE_DIVK2
- DP_PIXEL_PER_CYCLE_PROCESSING_MODE
- DIG_FIFO_OUTPUT_PIXEL_MODE
- DP_VID_N_MUL

Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>