[Why]
This option can vary depending on the panel and may be required to be
called during sink detection phase before transmitter control.

[How]
Allow modify the bit depending on the eDP panel connected with a new
interface.
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Paul Hsieh <paul.hsieh@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>