Simplify equals() method of ServiceState

For whatever reason, ServiceState used a
somewhat-convoluted check for null and
class type. Updating to use a canonical
and brief approach.

Bug: 8675309
Test: compilation
Change-Id: I0d635067a06093affff478e13c28bbbe2bfda7df
diff --git a/telephony/java/android/telephony/ServiceState.java b/telephony/java/android/telephony/ServiceState.java
index e86b482..ccb4ef8 100644
--- a/telephony/java/android/telephony/ServiceState.java
+++ b/telephony/java/android/telephony/ServiceState.java
@@ -756,17 +756,8 @@
 
     @Override
     public boolean equals (Object o) {
-        ServiceState s;
-
-        try {
-            s = (ServiceState) o;
-        } catch (ClassCastException ex) {
-            return false;
-        }
-
-        if (o == null) {
-            return false;
-        }
+        if (!(o instanceof ServiceState)) return false;
+        ServiceState s = (ServiceState) o;
 
         return (mVoiceRegState == s.mVoiceRegState
                 && mDataRegState == s.mDataRegState