net, compat_ioctl: fix SIOCGMII ioctls

SIOCGMIIPHY and SIOCGMIIREG return data through ifreq,
so it needs to be converted on the way out as well.

SIOCGIFPFLAGS is unused, but has the same problem in theory.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>