dialog_ng: set kamailio mod interface always

- it breaks rpc list generation otherwise
(cherry picked from commit 11bc294a9d64e31014ccb836290467984c28ce65)

modules/dialog_ng/Makefile

@@ -7,9 +7,7 @@ auto_gen=
 NAME=dialog_ng.so
 LIBS= 
 
-ifeq ($(CFG_NAME),kamailio)
-	DEFS += -DKAMAILIO_MOD_INTERFACE
-endif
+DEFS += -DKAMAILIO_MOD_INTERFACE
 
 SERLIBPATH=../../lib
 SER_LIBS+=$(SERLIBPATH)/kmi/kmi