ipq806x: fix "reboot" command

ipq806x: fix "reboot" command

The watchdog driver already registers a restart notifier, we just have
to enable it in the config and in the DT to fix the "reboot" command.

This is done by integratin the following patch-set:
https://lkml.org/lkml/2015/2/20/610

I'm copy-pasting the description below:
qcom-wdt is currently assuming the presence of a dedicated node in DT
to gets its configuration. However, on msm architecture, the watchdog is
usually part of the timer block. So this patch-set is changing the driver
and slightly enhancing the timer DT bindings to provide the relevant clocks
and interrupts.

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44504 3c298f89-4303-0410-b956-a3cf2f4a3e73