drm/amd/display: Add a debug option HBR2CP2520 over TPS4

[Why & How] There are cases when we may need to override the hardcoded
TPS4 test pattern. Added parameters and config option to be able to
allow this.

Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Leo Chen <sancchen@amd.com>
Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>