drm/radeon: export max link rate calculation

We need this in the MST code later.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/atombios_dp.c

@@ -310,7 +310,7 @@ static int dp_get_max_dp_pix_clock(int link_rate,
 
 /***** radeon specific DP functions *****/
 
-static int radeon_dp_get_max_link_rate(struct drm_connector *connector,
+int radeon_dp_get_max_link_rate(struct drm_connector *connector,
 				u8 dpcd[DP_DPCD_SIZE])
 {
 	int max_link_rate;

drivers/gpu/drm/radeon/radeon_mode.h

@@ -719,6 +719,8 @@ extern u8 radeon_dp_getsinktype(struct radeon_connector *radeon_connector);
 extern bool radeon_dp_getdpcd(struct radeon_connector *radeon_connector);
 extern int radeon_dp_get_panel_mode(struct drm_encoder *encoder,
 				    struct drm_connector *connector);
+int radeon_dp_get_max_link_rate(struct drm_connector *connector,
+				u8 *dpcd);
 extern void radeon_dp_set_rx_power_state(struct drm_connector *connector,
 					 u8 power_state);
 extern void radeon_dp_aux_init(struct radeon_connector *radeon_connector);