drm/gma500: Add IS_CDV() macro

This macro is needed for Cedarview specific stuff in the generic gma
functions.
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>

drivers/gpu/drm/gma500/psb_drv.h

@@ -47,6 +47,7 @@ enum {
 #define IS_PSB(dev) (((dev)->pci_device & 0xfffe) == 0x8108)
 #define IS_MRST(dev) (((dev)->pci_device & 0xfffc) == 0x4100)
 #define IS_MFLD(dev) (((dev)->pci_device & 0xfff8) == 0x0130)
+#define IS_CDV(dev) (((dev)->pci_device & 0xfff0) == 0x0be0)
 
 /*
  * Driver definitions