MIPS: BCM63XX: don't write to the chipid register on reboot

While harmless, it is bad style to do so.

Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/4092/


Signed-off-by: John Crispin <blogic@openwrt.org>