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/wireless/rtl818x/rtl8180/dev.c b/drivers/net/wireless/rtl818x/rtl8180/dev.c
index 0082015..2f14a5f 100644
--- a/drivers/net/wireless/rtl818x/rtl8180/dev.c
+++ b/drivers/net/wireless/rtl818x/rtl8180/dev.c
@@ -22,6 +22,7 @@
 #include <linux/delay.h>
 #include <linux/etherdevice.h>
 #include <linux/eeprom_93cx6.h>
+#include <linux/module.h>
 #include <net/mac80211.h>
 
 #include "rtl8180.h"