cpuidle: mvebu: add Armada 370 support

This commit adds the list of cpuidle states supported by the Armada
370 SoC in the cpuidle-mvebu-v7 driver, as well as the necessary logic
around it to support this SoC.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lkml.kernel.org/r/1406120453-29291-13-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>