Use correct error code for rate limiting.

Note that this CL depends on cl 712195, which must be submitted first.

Bug: 21607106
Change-Id: Iafc42d1c8a1145a31ea252b33b404044f92ec62b
diff --git a/cryptfs.c b/cryptfs.c
index 23bf2e1..bde0f26 100644
--- a/cryptfs.c
+++ b/cryptfs.c
@@ -350,7 +350,7 @@
         keymaster_error_t error = keymaster1_dev->begin(keymaster1_dev, KM_PURPOSE_SIGN, &key,
                                                         &param_set, NULL /* out_params */,
                                                         &op_handle);
-        if (error == KM_ERROR_VERIFICATION_FAILED) {
+        if (error == KM_ERROR_KEY_RATE_LIMIT_EXCEEDED) {
             // Key usage has been rate-limited.  Wait a bit and try again.
             sleep(KEYMASTER_CRYPTFS_RATE_LIMIT);
             error = keymaster1_dev->begin(keymaster1_dev, KM_PURPOSE_SIGN, &key,