ethtool: Fix build due to lack of ethtool.h include.

net/core/ethtool.c: In function 'ethtool_get_regs':
net/core/ethtool.c:818:2: error: implicit declaration of function 'vmalloc'
net/core/ethtool.c:818:9: warning: assignment makes pointer from integer without a cast
net/core/ethtool.c:833:2: error: implicit declaration of function 'vfree'

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index dae2fd0..7d7e572 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -19,6 +19,7 @@
 #include <linux/netdevice.h>
 #include <linux/bitops.h>
 #include <linux/uaccess.h>
+#include <linux/vmalloc.h>
 #include <linux/slab.h>
 
 /*