Remove deprecated module (ARMmbed#35)

arm_uc_paal_update_api.h file has been moved to
ARMmbed/update-client-paal

Author: LiyouZhou

source/active_application.h

@@ -12,7 +12,7 @@
 //   from ARM Limited or its affiliates.
 //----------------------------------------------------------------------------
 
-#include "paal-update-api/arm_uc_paal_update_api.h"
+#include "update-client-paal/arm_uc_paal_update_api.h"
 
 #include "pal.h"