watchdog: qcom: use timer devicetree binding

MSM watchdog configuration happens in the same register block as the
timer, so we'll use the same binding as the existing timer.

The qcom-wdt will now be probed when devicetree has an entry compatible
with "qcom,kpss-timer" or "qcom-scss-timer".

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>