MIPS: lantiq: reboot gphy on restart

A reboot sometimes lead to a none working phy. An explicit reboot fixes the
problem.

Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/8044/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>