drm/radeon/kms: register an i2c adapter name for the dp aux bus

This causes the connector to not be added since i2c init fails
for the adapter.  Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=31688

Noticed by Ari Savolainen.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: Ari Savolainen <ari.m.savolainen@gmail.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_i2c.c

@@ -946,6 +946,7 @@ struct radeon_i2c_chan *radeon_i2c_create_dp(struct drm_device *dev,
 	i2c->rec = *rec;
 	i2c->adapter.owner = THIS_MODULE;
 	i2c->dev = dev;
+	sprintf(i2c->adapter.name, "Radeon aux bus %s", name);
 	i2c_set_adapdata(&i2c->adapter, i2c);
 	i2c->adapter.algo_data = &i2c->algo.dp;
 	i2c->algo.dp.aux_ch = radeon_dp_i2c_aux_ch;