drm/i915: Use i9xx_check_plane_surface() for sprite planes as well

All the pre-SKL sprite planes compute the x/y/tile offsets in a
similar way. There are a couple of minor differences but the primary
planes have those as well. Thus i9xx_check_plane_surface()
already does what we need, so let's use it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170323192712.30682-7-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_drv.h

@@ -1453,6 +1453,7 @@ u32 skl_plane_ctl(const struct intel_crtc_state *crtc_state,
 u32 skl_plane_stride(const struct drm_framebuffer *fb, int plane,
 		     unsigned int rotation);
 int skl_check_plane_surface(struct intel_plane_state *plane_state);
+int i9xx_check_plane_surface(struct intel_plane_state *plane_state);
 
 /* intel_csr.c */
 void intel_csr_ucode_init(struct drm_i915_private *);