Add support for programming the DCN3 OPTC (Output Timing Controller)

HW Blocks:

    +--------+
    |  OPTC  |
    +--------+
        |
        v
    +--------+       +--------+
    |  DIO   |       |  DCCG  |
    +--------+       +--------+
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>