drm/radeon/kms: refine TMDS dual link checks

HDMI 1.3 defines single link clocks up to 340 Mhz.
Refine the current dual link checks to only enable
dual link for DVI > 165 Mhz or HDMI > 340 Mhz if the
hw supports HDMI 1.3 (DCE3+).

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=44755

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index d34dcb6..4330e32 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -467,6 +467,10 @@
 
 extern struct drm_connector *
 radeon_get_connector_for_encoder(struct drm_encoder *encoder);
+extern struct drm_connector *
+radeon_get_connector_for_encoder_init(struct drm_encoder *encoder);
+extern bool radeon_dig_monitor_is_duallink(struct drm_encoder *encoder,
+				    u32 pixel_clock);
 
 extern u16 radeon_encoder_get_dp_bridge_encoder_id(struct drm_encoder *encoder);
 extern u16 radeon_connector_encoder_get_dp_bridge_encoder_id(struct drm_connector *connector);