[AGPGART] Prevent (unlikely) memory leak in amd_create_gatt_pages()

If we fail an alloc, unwind the previous allocs that succeeded.
Spotted-by: NAlan Grimes <agrimes@speakeasy.net>
Signed-off-by: NDave Jones <davej@redhat.com>

drivers/char/agp/amd-k7-agp.c

@@ -101,6 +101,11 @@ static int amd_create_gatt_pages(int nr_tables)
 	for (i = 0; i < nr_tables; i++) {
 		entry = kzalloc(sizeof(struct amd_page_map), GFP_KERNEL);
 		if (entry == NULL) {
+			while (i > 0) {
+				kfree(tables[i-1]);
+				i--;
+			}
+			kfree(tables);
 			retval = -ENOMEM;
 			break;
 		}