Now that mbufs are allocated using uma,

don't check for accidental usage of mbuf 'how' flags as
they are the same thing.

sys/netgraph/ng_message.h

@@ -371,10 +371,6 @@ struct flow_manager {
  */
 #define NG_MKMESSAGE(msg, cookie, cmdid, len, how)			\
 	do {								\
-	  KASSERT(!(how & M_DONTWAIT),					\
-	      ("NG_MKMESSAGE() with how=M_DONTWAIT (%d)\n", how));	\
-	  KASSERT(!(how & M_TRYWAIT),					\
-	      ("NG_MKMESSAGE() with how=M_TRYWAIT (%d)\n", how));	\
 	  MALLOC((msg), struct ng_mesg *, sizeof(struct ng_mesg)	\
 	    + (len), M_NETGRAPH_MSG, (how) | M_ZERO);			\
 	  if ((msg) == NULL)						\