netxen: netxen_rom_fast_read() doesn't return -1

The error handling is broken here.  netxen_rom_fast_read() returns zero
on success and -EIO on error.  It never returns -1.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>