clocksource: time-armada-370-xp: add suspend/resume support

This commit adds a set of suspend/resume syscore_ops to respectively
save and restore a number of timer registers, in order to make sure
the clockevent and clocksource devices continue to work properly
across a suspend/resume cycle.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lkml.kernel.org/r/1416585613-2113-5-git-send-email-thomas.petazzoni@free-electrons.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>