LocationManagerService: Fix null pointer check in sendExtraCommand().

Signed-off-by: Mike Lockwood <lockwood@android.com>

services/java/com/android/server/LocationManagerService.java

@@ -1110,7 +1110,7 @@ public class LocationManagerService extends ILocationManager.Stub implements Run
 
         synchronized (mLock) {
             LocationProviderProxy proxy = mProvidersByName.get(provider);
-            if (provider == null) {
+            if (proxy == null) {
                 return false;
             }