brcm47xx: make reboot a more reliable

brcm47xx: make reboot a more reliable

A reboot is issued by setting the watchdog timer to a low value, when
the value is decreased from 1 to 0 by the hardware the system will
reboot. Setting this value to 1 does not work every time, it is a
little bit more reliable when setting it to 3. This timer runs with
some MHz or KHz so nobody will notice the increased waiting.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41548 3c298f89-4303-0410-b956-a3cf2f4a3e73