drm/i915/tgl: Add missing ddi clock select during DP init sequence

Step 4.b was complete missed because it is only required to TC and TBT.

Bspec: 49190
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Clinton A Taylor <clinton.a.taylor@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190920205810.211048-2-jose.souza@intel.com

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -3230,11 +3230,14 @@ static void tgl_ddi_pre_enable_dp(struct intel_encoder *encoder,
 	intel_edp_panel_on(intel_dp);
 
 	/*
-	 * 1.b, 3. and 4. is done before tgl_ddi_pre_enable_dp() by:
+	 * 1.b, 3. and 4.a is done before tgl_ddi_pre_enable_dp() by:
 	 * haswell_crtc_enable()->intel_encoders_pre_pll_enable() and
 	 * haswell_crtc_enable()->intel_enable_shared_dpll()
 	 */
 
+	/* 4.b */
+	intel_ddi_clk_select(encoder, crtc_state);
+
 	/* 5. */
 	if (!intel_phy_is_tc(dev_priv, phy) ||
 	    dig_port->tc_mode != TC_PORT_TBT_ALT)