Add support for ps4 encoder to radeon driver

Not terribly happy with how this is hooked up, but it could be way
worse.

Author: marcan

drivers/gpu/drm/radeon/Makefile

@@ -81,6 +81,8 @@ radeon-y += radeon_device.o radeon_asic.o radeon_kms.o \
 
 radeon-$(CONFIG_MMU_NOTIFIER) += radeon_mn.o
 
+radeon-$(CONFIG_X86_PS4) += ps4_bridge.o
+
 # add async DMA block
 radeon-y += \
 	r600_dma.o \

drivers/gpu/drm/radeon/atombios_encoders.c

@@ -687,7 +687,8 @@ atombios_get_encoder_mode(struct drm_encoder *encoder)
 	if (radeon_encoder->is_mst_encoder || radeon_encoder->offset)
 		return ATOM_ENCODER_MODE_DP_MST;
 	/* dp bridges are always DP */
-	if (radeon_encoder_get_dp_bridge_encoder_id(encoder) != ENCODER_OBJECT_ID_NONE)
+	if (radeon_encoder_get_dp_bridge_encoder_id(encoder) != ENCODER_OBJECT_ID_NONE ||
+	    rdev->family == CHIP_LIVERPOOL)
 		return ATOM_ENCODER_MODE_DP;
 
 	/* DVO is always DVO */