drm/i915: check for return value

We were not checking the return value of drm_encoder_init() which can
fail. And if it fails then we will be working with an uninitialized
encoder.

Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: NSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1444312681-10149-2-git-send-email-sudipm.mukherjee@gmail.com

drivers/gpu/drm/i915/intel_dp.c

@@ -5987,8 +5987,9 @@ intel_dp_init(struct drm_device *dev,
 	intel_encoder = &intel_dig_port->base;
 	encoder = &intel_encoder->base;
 
-	drm_encoder_init(dev, &intel_encoder->base, &intel_dp_enc_funcs,
-			 DRM_MODE_ENCODER_TMDS);
+	if (drm_encoder_init(dev, &intel_encoder->base, &intel_dp_enc_funcs,
+			     DRM_MODE_ENCODER_TMDS))
+		goto err_encoder_init;
 
 	intel_encoder->compute_config = intel_dp_compute_config;
 	intel_encoder->disable = intel_disable_dp;
@@ -6037,6 +6038,7 @@ intel_dp_init(struct drm_device *dev,
 
 err_init_connector:
 	drm_encoder_cleanup(encoder);
+err_encoder_init:
 	kfree(intel_connector);
 err_connector_alloc:
 	kfree(intel_dig_port);