drm/amd/display: switch to drm_dbg_kms() from DRM_DEBUG_KMS

drm/amd/display: switch to drm_dbg_kms() from DRM_DEBUG_KMS

DRM_DEBUG_ class of macros are depricated. Recommended drm_dbg_kms() has
the advantage of being able to distinguish the logs from devices in a
multi-gpu environment.

Where a pointer to struct amdgpu_device is available, use that to get
the drm device.

Reviewed-by: Sun peng (Leo) Li <sunpeng.li@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>