drm/amd/display: Implement new backlight_level_params structure

[Why]
Implement the new backlight_level_params structure as part of the VBAC
framework, the information in this structure is needed to be passed down
to the DMCUB to identify the backlight control type, to adjust the
backlight of the panel and to perform any required conversions from PWM
to nits or vice versa.

[How]
Modified existing functions to include the new backlight_level_params
structure.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Kaitlyn Tse <Kaitlyn.Tse@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>