gma500: fix build warning

 CC [M]  drivers/gpu/drm/i915/i915_gem_evict.o
/ssd/git/drm-core-next/drivers/gpu/drm/gma500/psb_device.c: In function ‘psb_chip_errata’:
/ssd/git/drm-core-next/drivers/gpu/drm/gma500/psb_device.c:360:1: warning: no return statement in function returning non-void [-Wreturn-type]
/ssd/git/drm-core-next/drivers/gpu/drm/gma500/psb_device.c: At top level:
/ssd/git/drm-core-next/drivers/gpu/drm/gma500/psb_device.c:379:2: warning: initialization from incompatible pointer type [enabled by default]
/ssd/git/drm-core-next/drivers/gpu/drm/gma500/psb_device.c:379:2: warning: (near initialization for ‘psb_chip_ops.errata’) [enabled by default]
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/psb_device.c

@@ -353,7 +353,7 @@ static int psb_chip_setup(struct drm_device *dev)
 }
 
 /* Not exactly an erratum more an irritation */
-static int psb_chip_errata(struct drm_device *dev)
+static void psb_chip_errata(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = dev->dev_private;
 	psb_lid_timer_init(dev_priv);