thermal: tango: add resume support

When this platform is suspended, firmware powers the entire SoC down,
except a few hardware blocks waiting for wakeup events. There is no
context to save for this particular block.

Therefore, there is nothing useful for the driver to do on suspend;
so we define a NULL suspend hook. On resume, the driver initializes
the block exactly as is done in the probe callback.

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>