thermal: imx: correct suspend/resume flow

thermal: imx: correct suspend/resume flow

Fixes regression introduced by:

commit 37713a1e8e4c1a1067ad4c99296f78d3c82ed9c4
Author: Philipp Zabel <p.zabel@pengutronix.de>
Date:   Thu Aug 1 18:33:12 2013 +0200

    thermal: imx: implement thermal alarm interrupt handling

The commit 37713a1e8e4 makes imx thermal sensor always powered up as alarm
function is enabled, but the suspend callback of imx thermal returns
success only if thermal sensor is powered down, so it will always returns
fail hence break system's suspend, this patch disables imx thermal sensor
before suspend and re-enable it after resume.

Signed-off-by: Anson Huang <b20788@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>