drm/i915: Give encoders useful names

Rather than let the core generate usless encoder names, let's pass in
something that actually identifies the piece of hardware we're dealing
with.

v2: Use 'DSI %c' instead of 'MIPI %c' for DSI encoders (Jani)
v3: Use port_name() in DSI code since we have it

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464371966-15190-7-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 3fbb6fc..6229681 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -839,7 +839,7 @@
 			   &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);
 
 	drm_encoder_init(dev, &crt->base.base, &intel_crt_enc_funcs,
-			 DRM_MODE_ENCODER_DAC, NULL);
+			 DRM_MODE_ENCODER_DAC, "CRT");
 
 	intel_connector_attach_encoder(intel_connector, &crt->base);