drm/i915: add support for E7221 chipset

E7221 chipset is a server version of the i915.
Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/char/drm/i915_drv.h

@@ -1075,7 +1075,7 @@ extern int i915_wait_ring(struct drm_device * dev, int n, const char *caller);
 #define IS_I855(dev) ((dev)->pci_device == 0x3582)
 #define IS_I865G(dev) ((dev)->pci_device == 0x2572)
 
-#define IS_I915G(dev) (dev->pci_device == 0x2582)/* || dev->pci_device == PCI_DEVICE_ID_INTELPCI_CHIP_E7221_G)*/
+#define IS_I915G(dev) ((dev)->pci_device == 0x2582 || (dev)->pci_device == 0x258a)
 #define IS_I915GM(dev) ((dev)->pci_device == 0x2592)
 #define IS_I945G(dev) ((dev)->pci_device == 0x2772)
 #define IS_I945GM(dev) ((dev)->pci_device == 0x27A2)