SipSettings: use SipErrorCode instead of string.

Change-Id: I98579d09c953aa2791fbd1374925479aada48938
diff --git a/src/com/android/phone/sip/SipSettings.java b/src/com/android/phone/sip/SipSettings.java
index 49e1966..fd519c8 100644
--- a/src/com/android/phone/sip/SipSettings.java
+++ b/src/com/android/phone/sip/SipSettings.java
@@ -431,8 +431,8 @@
             }
 
             public void onRegistrationFailed(String profileUri,
-                    String errorCodeString, String message) {
-                switch (Enum.valueOf(SipErrorCode.class, errorCodeString)) {
+                    SipErrorCode errorCode, String message) {
+                switch (errorCode) {
                     case IN_PROGRESS:
                         showRegistrationMessage(profileUri, getString(
                                 R.string.registration_status_still_trying));