drm/amd/display: add DC drm_panic support

Add support for the drm_panic module, which displays a pretty user
friendly message on the screen when a Linux kernel panic occurs.

It doesn't work yet on laptop panels, maybe due to PSR.

Adapted from Jocelyn's original patch to add DC drm_panic
support.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Lu Yao <yaolu@kylinos.cn>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Harry Wentland <harry.wentland@amd.com>