net: fddi: fix UAF in fza_probe

fp is netdev private data and it cannot be
used after free_netdev() call. Using fp after free_netdev()
can cause UAF bug. Fix it by moving free_netdev() after error message.

Fixes: 61414f5e ("FDDI: defza: Add support for DEC FDDIcontroller 700
TURBOchannel adapter")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>