Compilation fix: using enum SUCCESS instead of MQTTASYNC_SUCCESS

This commit fixes compilation error:
MQTTAsync.h:1114:143: error: invalid conversion
from ‘int’ to ‘MQTTReasonCodes’ [-fpermissive]
Signed-off-by: Krzysztof Bogucki <kristofbo@gmail.com>

src/MQTTAsync.h

@@ -1111,7 +1111,7 @@ typedef struct
 	MQTTAsync_onFailure5* onFailure5;
 } MQTTAsync_disconnectOptions;
 
-#define MQTTAsync_disconnectOptions_initializer { {'M', 'Q', 'T', 'D'}, 1, 0, NULL, NULL, NULL, MQTTProperties_initializer, MQTTASYNC_SUCCESS }
+#define MQTTAsync_disconnectOptions_initializer { {'M', 'Q', 'T', 'D'}, 1, 0, NULL, NULL, NULL, MQTTProperties_initializer, SUCCESS }
 
 
 /**