Fix string equality comparison

Don't use "==" to compare strings.

Bug: 25624963
Change-Id: Id25696e4fdcbcf4d48ec74e8ed65c1a33716b30c
diff --git a/wifi/java/android/net/wifi/WifiEnterpriseConfig.java b/wifi/java/android/net/wifi/WifiEnterpriseConfig.java
index 16035ad..a337755 100644
--- a/wifi/java/android/net/wifi/WifiEnterpriseConfig.java
+++ b/wifi/java/android/net/wifi/WifiEnterpriseConfig.java
@@ -769,7 +769,7 @@
         StringBuffer sb = new StringBuffer();
         for (String key : mFields.keySet()) {
             // Don't display password in toString().
-            String value = (key == PASSWORD_KEY) ? "<removed>" : mFields.get(key);
+            String value = PASSWORD_KEY.equals(key) ? "<removed>" : mFields.get(key);
             sb.append(key).append(" ").append(value).append("\n");
         }
         return sb.toString();