drm/i915/skl: Use fb modifiers for sprites

While at it just outright remove the tiling check in
intel_check_sprite_plane because it's impossible: We only allow
untiled and X-tiled. This essentially reverts

commit 94c6419ed8f45e6682d766672b9ceb54867d3d2d
Author: Damien Lespiau <damien.lespiau@intel.com>
Date:   Mon Oct 29 15:14:51 2012 +0000

    drm/i915: Error out when trying to set a y-tiled as a sprite

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
[danvet: Drop the hunk in check_sprite, it's impossible.]
Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sprite.c

@@ -245,11 +245,11 @@ skl_update_plane(struct drm_plane *drm_plane, struct drm_crtc *crtc,
 		BUG();
 	}
 
-	switch (obj->tiling_mode) {
-	case I915_TILING_NONE:
+	switch (fb->modifier[0]) {
+	case DRM_FORMAT_MOD_NONE:
 		stride = fb->pitches[0] >> 6;
 		break;
-	case I915_TILING_X:
+	case I915_FORMAT_MOD_X_TILED:
 		plane_ctl |= PLANE_CTL_TILED_X;
 		stride = fb->pitches[0] >> 9;
 		break;
@@ -1076,7 +1076,6 @@ intel_check_sprite_plane(struct drm_plane *plane,
 	struct intel_crtc *intel_crtc = to_intel_crtc(state->base.crtc);
 	struct intel_plane *intel_plane = to_intel_plane(plane);
 	struct drm_framebuffer *fb = state->base.fb;
-	struct drm_i915_gem_object *obj = intel_fb_obj(fb);
 	int crtc_x, crtc_y;
 	unsigned int crtc_w, crtc_h;
 	uint32_t src_x, src_y, src_w, src_h;
@@ -1106,16 +1105,6 @@ intel_check_sprite_plane(struct drm_plane *plane,
 		return -EINVAL;
 	}
 
-	/* Sprite planes can be linear or x-tiled surfaces */
-	switch (obj->tiling_mode) {
-		case I915_TILING_NONE:
-		case I915_TILING_X:
-			break;
-		default:
-			DRM_DEBUG_KMS("Unsupported tiling mode\n");
-			return -EINVAL;
-	}
-
 	/*
 	 * FIXME the following code does a bunch of fuzzy adjustments to the
 	 * coordinates and sizes. We probably need some way to decide whether