net: compat: No need to define IFHWADDRLEN and IFNAMSIZ twice.

It's defined colloqually in linux/if.h and linux/compat.h
includes that.
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/compat.h

@@ -166,8 +166,6 @@ struct compat_ifmap {
 };
 
 struct compat_ifreq {
-#define IFHWADDRLEN     6
-#define IFNAMSIZ        16
         union {
                 char    ifrn_name[IFNAMSIZ];            /* if name, e.g. "en0" */
         } ifr_ifrn;