drm/radeon/kms: fix some GART table entry bugs.

1. rv370 can accept 40-bit addresses - also at 24-bit shift not 4 bits
2. rs480 table can be in 40-bit space. - 4 bit shift for top 8 bits
3. rs480 table entries can be in 40-bit space.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r300.c b/drivers/gpu/drm/radeon/r300.c
index e2ed5bc..cd9ea98 100644
--- a/drivers/gpu/drm/radeon/r300.c
+++ b/drivers/gpu/drm/radeon/r300.c
@@ -150,7 +150,9 @@
 	if (i < 0 || i > rdev->gart.num_gpu_pages) {
 		return -EINVAL;
 	}
-	addr = (((u32)addr) >> 8) | ((upper_32_bits(addr) & 0xff) << 4) | 0xC;
+	addr = (lower_32_bits(addr) >> 8) |
+	       ((upper_32_bits(addr) & 0xff) << 24) |
+	       0xc;
 	writel(cpu_to_le32(addr), ((void __iomem *)ptr) + (i * 4));
 	return 0;
 }