drm/i915: Add main atomic entrypoints (v2)

Add the top-level atomic entrypoints for check/commit.  These won't get
called yet; we still need to either enable the atomic ioctl or switch to
using the non-transitional atomic helpers for legacy operations.

v2:
 - Use plane->pipe rather than plane->possible_crtcs while ensuring that
   only a single CRTC is in use.  Either way will work fine since i915
   drm_plane's are always tied to a single CRTC, but plane->pipe is
   slightly more intuitive. (Ander)
 - Simplify crtc/connector checking logic. (Ander)

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0cdcf9b..75b7ca1 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12752,6 +12752,8 @@
 static const struct drm_mode_config_funcs intel_mode_funcs = {
 	.fb_create = intel_user_framebuffer_create,
 	.output_poll_changed = intel_fbdev_output_poll_changed,
+	.atomic_check = intel_atomic_check,
+	.atomic_commit = intel_atomic_commit,
 };
 
 /* Set up chip specific display functions */