[AGPGART] Mark AMD64 aperture size structs as const

Neither of them are ever written to.

Noted by Arjan van de Ven
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c
index 7658978..810679d 100644
--- a/drivers/char/agp/amd64-agp.c
+++ b/drivers/char/agp/amd64-agp.c
@@ -416,7 +416,7 @@
 }
 
 
-static struct aper_size_info_32 uli_sizes[7] =
+static const struct aper_size_info_32 uli_sizes[7] =
 {
 	{256, 65536, 6, 10},
 	{128, 32768, 5, 9},
@@ -470,7 +470,7 @@
 }
 
 
-static struct aper_size_info_32 nforce3_sizes[5] =
+static const struct aper_size_info_32 nforce3_sizes[5] =
 {
 	{512,  131072, 7, 0x00000000 },
 	{256,  65536,  6, 0x00000008 },