Cleanup some warning from timestamping code.

Following checkpatch.pl recommendations (which include
replacing with <linux/io.h> the <asm/io.h>, since linux/io.h includes
it).
Signed-off-by: NEzequiel Lara Gomez <ezegomez@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/loopback.c

@@ -41,7 +41,7 @@
 #include <linux/in.h>
 
 #include <linux/uaccess.h>
-#include <asm/io.h>
+#include <linux/io.h>
 
 #include <linux/inet.h>
 #include <linux/netdevice.h>
@@ -65,8 +65,7 @@ struct pcpu_lstats {
 	struct u64_stats_sync	syncp;
 };
 
-/*
- * The higher levels take care of making this non-reentrant (it's
+/* The higher levels take care of making this non-reentrant (it's
  * called with bh's disabled).
  */
 static netdev_tx_t loopback_xmit(struct sk_buff *skb,
@@ -165,13 +164,12 @@ static void loopback_dev_free(struct net_device *dev)
 
 static const struct net_device_ops loopback_ops = {
 	.ndo_init        = loopback_dev_init,
-	.ndo_start_xmit= loopback_xmit,
+	.ndo_start_xmit  = loopback_xmit,
 	.ndo_get_stats64 = loopback_get_stats64,
 	.ndo_set_mac_address = eth_mac_addr,
 };
 
-/*
- * The loopback device is special. There is only one instance
+/* The loopback device is special. There is only one instance
  * per network namespace.
  */
 static void loopback_setup(struct net_device *dev)
@@ -221,7 +219,6 @@ static __net_init int loopback_net_init(struct net *net)
 	net->loopback_dev = dev;
 	return 0;
 
-
 out_free_netdev:
 	free_netdev(dev);
 out: