Annotated dprintf as printf-like

ZFS loves using %llu for uint64_t, but that requires a cast to not 
be noisy - which is even done in many, though not all, places.
Also a couple places used %u for uint64_t, which were promoted
to %llu. 

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12233

module/zfs/zcp.c

@@ -654,7 +654,8 @@ zcp_debug(lua_State *state)
 
 	dbgstring = lua_tostring(state, 1);
 
-	zfs_dbgmsg("txg %lld ZCP: %s", ri->zri_tx->tx_txg, dbgstring);
+	zfs_dbgmsg("txg %lld ZCP: %s", (longlong_t)ri->zri_tx->tx_txg,
+	    dbgstring);
 
 	return (0);
 }