drm/i915: Dump pipe config when intel_modeset_pipe_config fails.

This makes it easier to debug issues like https://bugs.freedesktop.org/show_bug.cgi?id=93477

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Chris Wilson <|chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/843f4327-1574-cf8e-0776-adbb0d58c2c0@mblankhorst.nl
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -13378,8 +13378,11 @@ static int intel_atomic_check(struct drm_device *dev,
 			return ret;
 
 		ret = intel_modeset_pipe_config(crtc, pipe_config);
-		if (ret)
+		if (ret) {
+			intel_dump_pipe_config(to_intel_crtc(crtc),
+					       pipe_config, "[failed]");
 			return ret;
+		}
 
 		if (i915.fastboot &&
 		    intel_pipe_config_compare(dev,