drm/amd/display: Expose OTG_V_TOTAL_MID for HW Diags

[Why]
Existing HW Features, HW Diags test requested that the
registers be exposed.

[How]
Add V_TOTAL_MID to existing DC structures.
Make sure values are passed down throughout DC
Add Register definition.
Program the additional registers
Add additional Logic for V_TOTAL_CONTROL.

Signed-off-by: Bayan Zabihiyan <bayan.zabihiyan@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>