vtnet, ptnet: include opt_*.h files early

Include opt_inet.h and opt_inet6.h early in the files including
virtio_net.h, since they use INET and/or INET6.
While there, remove redundant inclusion of sys/types.h, since it is
included already by sys/param.h.

There was a discussion to include opt_inet.h and opt_inet6.h also
in virtio_net.h. glebius suggested to add a mechanism for files
to check, if required opt_*.h files were included. virtio_net.h
will be the first consumer of this mechanism.

Reviewed by:		glebius, Peter Lei
MFC after:		3 days
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D52046

Author: tuexen

sys/dev/netmap/if_ptnet.c

@@ -27,8 +27,9 @@
 /* Driver for ptnet paravirtualized network device. */
 
 #include <sys/cdefs.h>
+#include "opt_inet.h"
+#include "opt_inet6.h"
 
-#include <sys/types.h>
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
@@ -75,9 +76,6 @@
 #include <dev/pci/pcivar.h>
 #include <dev/pci/pcireg.h>
 
-#include "opt_inet.h"
-#include "opt_inet6.h"
-
 #include <sys/selinfo.h>
 #include <net/netmap.h>
 #include <dev/netmap/netmap_kern.h>

sys/dev/virtio/network/if_vtnet.c

@@ -28,6 +28,9 @@
 
 /* Driver for VirtIO network devices. */
 
+#include "opt_inet.h"
+#include "opt_inet6.h"
+
 #include <sys/param.h>
 #include <sys/eventhandler.h>
 #include <sys/systm.h>
@@ -82,9 +85,6 @@
 #include <dev/virtio/network/if_vtnetvar.h>
 #include "virtio_if.h"
 
-#include "opt_inet.h"
-#include "opt_inet6.h"
-
 #if defined(INET) || defined(INET6)
 #include <machine/in_cksum.h>
 #endif