drm/gma500: Add generic code for clock calculation

This patch aims to unify the bits and pieces that are common (or similar
enough) for pll clock calculations. Nothing makes use of this code yet
That will come in later patches.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>

drivers/gpu/drm/gma500/psb_drv.h

@@ -27,6 +27,7 @@
 #include <drm/gma_drm.h>
 #include "psb_reg.h"
 #include "psb_intel_drv.h"
+#include "gma_display.h"
 #include "intel_bios.h"
 #include "gtt.h"
 #include "power.h"
@@ -675,6 +676,7 @@ struct psb_ops {
 	/* Sub functions */
 	struct drm_crtc_helper_funcs const *crtc_helper;
 	struct drm_crtc_funcs const *crtc_funcs;
+	const struct gma_clock_funcs *clock_funcs;
 
 	/* Setup hooks */
 	int (*chip_setup)(struct drm_device *dev);