drm/i915/tc: fix the reset of ln0

Setting ln0 similar to ln1

Fixes: 3b51be4e ("drm/i915/tc: Update DP_MODE programming")
Cc: <stable@vger.kernel.org> # v5.5+
Signed-off-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200608204537.28468-1-khaled.almahallawy@intel.com
(cherry picked from commit 4f72a8ee)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

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

@@ -2987,7 +2987,7 @@ icl_program_mg_dp_mode(struct intel_digital_port *intel_dig_port,
 		ln1 = intel_de_read(dev_priv, MG_DP_MODE(1, tc_port));
 	}
 
-	ln0 &= ~(MG_DP_MODE_CFG_DP_X1_MODE | MG_DP_MODE_CFG_DP_X1_MODE);
+	ln0 &= ~(MG_DP_MODE_CFG_DP_X1_MODE | MG_DP_MODE_CFG_DP_X2_MODE);
 	ln1 &= ~(MG_DP_MODE_CFG_DP_X1_MODE | MG_DP_MODE_CFG_DP_X2_MODE);
 
 	/* DPPATC */