thermal: imx: correct suspend/resume flow

thermal: imx: correct suspend/resume flow

Fixes regression introduced by:

commit 2b0ddadac44eb5b7877bb504590fb90d438f53af
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 2b0ddadac44 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>