agp/intel: Use pci_bus_address() to get GTTADR bus address

Per the Intel 915G/915GV/... Chipset spec (document number 301467-005),
GTTADR is a standard PCI BAR.

The PCI core reads GTTADR at enumeration-time.  Use pci_bus_address()
instead of reading it again in the driver.  This works correctly for both
32-bit and 64-bit BARs.  The spec above only mentions 32-bit GTTADR, but we
should still use the standard interface.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/char/agp/intel-agp.h b/drivers/char/agp/intel-agp.h
index 18bbaaf..fda073d 100644
--- a/drivers/char/agp/intel-agp.h
+++ b/drivers/char/agp/intel-agp.h
@@ -115,7 +115,7 @@
 /* intel 915G registers */
 #define I915_GMADR_BAR	2
 #define I915_MMADR_BAR	0
-#define I915_PTEADDR	0x1C
+#define I915_PTE_BAR	3
 #define I915_GMCH_GMS_STOLEN_48M	(0x6 << 4)
 #define I915_GMCH_GMS_STOLEN_64M	(0x7 << 4)
 #define G33_GMCH_GMS_STOLEN_128M	(0x8 << 4)