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

If we fail an alloc, unwind the previous allocs that succeeded.

Spotted-by: Alan Grimes <agrimes@speakeasy.net>
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/drivers/char/agp/amd-k7-agp.c b/drivers/char/agp/amd-k7-agp.c
index 51d0d56..c85c8ca 100644
--- a/drivers/char/agp/amd-k7-agp.c
+++ b/drivers/char/agp/amd-k7-agp.c
@@ -101,6 +101,11 @@
 	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;
 		}