AccountManager: fix updateCredentials API.

Bug: 26157869
Change-Id: Icd2148db6923383263bcce5ad845bcb1411f5c4e
diff --git a/services/core/java/com/android/server/accounts/AccountManagerService.java b/services/core/java/com/android/server/accounts/AccountManagerService.java
index 8a0a62a..810270d 100644
--- a/services/core/java/com/android/server/accounts/AccountManagerService.java
+++ b/services/core/java/com/android/server/accounts/AccountManagerService.java
@@ -2884,7 +2884,6 @@
         }
         if (response == null) throw new IllegalArgumentException("response is null");
         if (account == null) throw new IllegalArgumentException("account is null");
-        if (authTokenType == null) throw new IllegalArgumentException("authTokenType is null");
         int userId = UserHandle.getCallingUserId();
         long identityToken = clearCallingIdentity();
         try {