m68k/atari: ARAnyM - Add support for network access

[petr: Second author]
[michael, geert: Cleanups and updates]

Signed-off-by: Milan Jurik <milan.jurik@xylab.cz>
Signed-off-by: Petr Stehlik <pstehlik@sophics.cz>
Signed-off-by: Michael Schmitz <schmitz@debian.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: netdev@vger.kernel.org