drm/amd/display: Implement transmitter control v1.7

[Why]
Moving definition of transmitter control from atomfirmware
to internal header.

[How]
Update the command table code to call 1.7 and make it the
default fallback path.

Signed-off-by: Eric Bernstein <eric.bernstein@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <Qingqing.Zhuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>