drm/kms/radeon: pick digitial encoders smarter. (v3)

booting a Lenovo W500 with LVDS + DP outputs showed up a TODO we had
on our list, to pick a correct digital encoder block. The LVTMA
encoder requires the second digital encoder, all others can use any
encoder at all.

This fixes the digital encoder selection logic to enable LVDS/DP combos
to work okay.

V2: fix silly addition of connector dig_block and cleanup the other
places in the code that pick the encoder.

V3: rename to dig_encoder and clean up further - also fix
the picking algorithm.

tested on Lenovo W500 + desktop 3650 cards.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 9c023d2..7106011 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -596,21 +596,14 @@
 		return;
 	dig_connector = radeon_connector->con_priv;
 
-	if (ASIC_IS_DCE32(rdev)) {
-		if (dig->dig_block)
-			enc_id |= ATOM_DP_CONFIG_DIG2_ENCODER;
-		else
-			enc_id |= ATOM_DP_CONFIG_DIG1_ENCODER;
-		if (dig_connector->linkb)
-			enc_id |= ATOM_DP_CONFIG_LINK_B;
-		else
-			enc_id |= ATOM_DP_CONFIG_LINK_A;
-	} else {
-		if (dig_connector->linkb)
-			enc_id |= ATOM_DP_CONFIG_DIG2_ENCODER | ATOM_DP_CONFIG_LINK_B;
-		else
-			enc_id |= ATOM_DP_CONFIG_DIG1_ENCODER | ATOM_DP_CONFIG_LINK_A;
-	}
+	if (dig->dig_encoder)
+		enc_id |= ATOM_DP_CONFIG_DIG2_ENCODER;
+	else
+		enc_id |= ATOM_DP_CONFIG_DIG1_ENCODER;
+	if (dig_connector->linkb)
+		enc_id |= ATOM_DP_CONFIG_LINK_B;
+	else
+		enc_id |= ATOM_DP_CONFIG_LINK_A;
 
 	memset(link_configuration, 0, DP_LINK_CONFIGURATION_SIZE);
 	if (dig_connector->dp_clock == 270000)