drivers/net: Add module.h to drivers who were implicitly using it

The device.h header was including module.h, making it present for
most of these drivers.  But we want to clean that up.  Call out the
include of module.h in the modular network drivers.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 5b23767..ef883e9 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -17,6 +17,7 @@
 #include <net/dst.h>
 #include <net/xfrm.h>
 #include <linux/veth.h>
+#include <linux/module.h>
 
 #define DRV_NAME	"veth"
 #define DRV_VERSION	"1.0"