drm/radeon: add Mullins chip family

Mullins is a new CI-based APU.

Signed-off-by: Samuel Li <samuel.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon_family.h b/drivers/gpu/drm/radeon/radeon_family.h
index 9da5da4..4b7b87f 100644
--- a/drivers/gpu/drm/radeon/radeon_family.h
+++ b/drivers/gpu/drm/radeon/radeon_family.h
@@ -97,6 +97,7 @@
 	CHIP_KAVERI,
 	CHIP_KABINI,
 	CHIP_HAWAII,
+	CHIP_MULLINS,
 	CHIP_LAST,
 };