drm/i915/skl: Allow scanning out Y and Yf fbs

Skylake is able to scannout those tiling formats. We need to allow them
in the ADDFB ioctl and tell the harware about it.

v2: Rebased for addfb2 interface. (Tvrtko Ursulin)
v3: Rebased for fb modifier changes. (Tvrtko Ursulin)
v4: Don't allow Y tiled fbs just yet. (Tvrtko Ursulin)
v5: Check for stride alignment and max pitch. (Tvrtko Ursulin)
v6: Simplify maximum pitch check. (Ville Syrjälä)
v7: Drop the gen9 check since requirements are no different. (Ville Syrjälä)
v8: Gen2 has different X tiling stride. (Ville Syrjälä)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com> (v7)
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 1fb1529..76df9d6 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -903,6 +903,8 @@
 			  uint64_t fb_format_modifier);
 void intel_fb_obj_flush(struct drm_i915_gem_object *obj, bool retire);
 
+u32 intel_fb_stride_alignment(struct drm_device *dev, uint64_t fb_modifier,
+			      uint32_t pixel_format);
 
 /* intel_audio.c */
 void intel_init_audio(struct drm_device *dev);