Fix panic on 4430 for the temp sensor idle

On 4430 the on-die temp sensor is not used.  But the CPU idle
path still calls the temp sensor idle.  This is not right

Only allow idle on 4460.

Change-Id: I1e9be21bc0d6d05c015d718121b04e01d905efb1
Signed-off-by: Dan Murphy <dmurphy@ti.com>
OMAP4470: TEMP_SENSOR: Thermal sensor support for 4470

Thermal sensor support is required by a new chip.

Add runtime checking for 4470 to allow usage of
thermal sensor.

Change-Id: I231826df11315a27d6174a8791c578a5abbb4257
Signed-off-by: Leonid Iziumtsev <x0153368@ti.com>