drm/amd/display: Read EDID from VBIOS embedded panel info

drm/amd/display: Read EDID from VBIOS embedded panel info

Some board manufacturers hardcode the EDID for the embedded
panel in the VBIOS. This EDID should be used when the panel
doesn't have a DDC.

For reference, see the legacy non-DC display code:
amdgpu_atombios_encoder_get_lcd_info()

This is necessary to support embedded connectors without DDC.

Fixes: 4562236b3bc0 ("drm/amd/dc: Add dc display driver (v2)")
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5192
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>