drm/ati_pcigart: fix the PCIGART to use drm_pci to allocate GART table.

This fixes a problem on 64-bit with 4GB with ATI RS690 chipsets. It
makes sure the pcigart table is allocated in coherent memory for DMA operations.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/char/drm/radeon_cp.c b/drivers/char/drm/radeon_cp.c
index 833abc7..9072e4a 100644
--- a/drivers/char/drm/radeon_cp.c
+++ b/drivers/char/drm/radeon_cp.c
@@ -1807,6 +1807,7 @@
 	} else
 #endif
 	{
+		dev_priv->gart_info.table_mask = DMA_BIT_MASK(32);
 		/* if we have an offset set from userspace */
 		if (dev_priv->pcigart_offset_set) {
 			dev_priv->gart_info.bus_addr =