Remove exra whitespace from files (#189)

* Remove multiple newlines at the end of files
* Remove the whitespace from the end of lines

net/netdev/netdev_carrier.c

@@ -108,4 +108,3 @@ int netdev_carrier_off(FAR struct net_driver_s *dev)
 
   return -EINVAL;
 }
-

net/netdev/netdev_count.c

@@ -75,4 +75,3 @@ int netdev_count(void)
   net_unlock();
   return ndev;
 }
-

net/netdev/netdev_default.c

@@ -99,4 +99,3 @@ FAR struct net_driver_s *netdev_default(void)
   net_unlock();
   return ret;
 }
-

net/netdev/netdev_findbyaddr.c

@@ -343,4 +343,3 @@ FAR struct net_driver_s *netdev_findby_ripv6addr(const net_ipv6addr_t lipaddr,
   return netdev_default();
 }
 #endif /* CONFIG_NET_IPv6 */
-

net/netdev/netdev_findbyindex.c

@@ -174,4 +174,3 @@ int netdev_nextindex(int ifindex)
   return -ENODEV;
 }
 #endif
-

net/netdev/netdev_findbyname.c

@@ -87,4 +87,3 @@ FAR struct net_driver_s *netdev_findbyname(FAR const char *ifname)
 
   return NULL;
 }
-

net/netdev/netdev_foreach.c

@@ -96,4 +96,3 @@ int netdev_foreach(netdev_callback_t callback, FAR void *arg)
 
   return ret;
 }
-

net/netdev/netdev_ioctl.c

@@ -1797,4 +1797,3 @@ void netdev_ifdown(FAR struct net_driver_s *dev)
 #endif
     }
 }
-

net/netdev/netdev_txnotify.c

@@ -145,4 +145,3 @@ void netdev_txnotify_dev(FAR struct net_driver_s *dev)
       dev->d_txavail(dev);
     }
 }
-

net/netdev/netdev_unregister.c

@@ -182,4 +182,3 @@ int netdev_unregister(FAR struct net_driver_s *dev)
 
   return -EINVAL;
 }
-