Mark ERROR_PUSH_OTHER_3000 as unused

* Per the last commit we no longer will be using "other 3000"
and instead this will always be ERROR_PUSH_CAPABLILITY_DISABLED instead.
* Keeping the define but post-fixing with "_UNUSED_RESERVED"
  - This is so we don't reuse this notification_types value later and
  keep this around so someone can git-blame to find this reasoning.

Author: jkasten2

iOS_SDK/OneSignalSDK/Source/OneSignalCommonDefines.h

@@ -221,7 +221,7 @@ typedef enum {GET, POST, HEAD, PUT, DELETE, OPTIONS, CONNECT, TRACE} HTTPMethod;
 #define ERROR_PUSH_DELEGATE_NEVER_FIRED    -14
 #define ERROR_PUSH_SIMULATOR_NOT_SUPPORTED -15
 #define ERROR_PUSH_UNKNOWN_APNS_ERROR      -16
-#define ERROR_PUSH_OTHER_3000_ERROR        -17
+#define ERROR_PUSH_OTHER_3000_ERROR_UNUSED_RESERVED -17
 #define ERROR_PUSH_NEVER_PROMPTED          -18
 #define ERROR_PUSH_PROMPT_NEVER_ANSWERED   -19