natsemi: sonic: stop calling netdev_boot_setup_check

The data from the kernel command line is no longer used since the
probe function gets it from the platform device resources instead.

The jazz version was changed to be like this in 2007, the xtensa
version apparently copied the code from there.

Fixes: ed9f0e0b ("remove setup of platform device from jazzsonic.c")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>