thermal: bandgap: Meld TSHUT config functions into one function

On OMAP4470 CONTROL_TSHUT_THRESHOLD was changed to one time writable
register, in difference to OMAP4460 where this register could be
rewrited at any time. Because of this we need to configure it using
one write operation.
So considering this, high and low thresholds should be configured
in one function. To accomplish that changing temp_sensor_configure_tshut_thigh()
and temp_sensor_configure_tlow() to just temp_sensor_configure_tshut().

Change-Id: Ib41b77f83cf07bd13c5a880dbd7cc652bdf73e77
Signed-off-by: Ruslan Ruslichenko <ruslan.ruslichenko@ti.com>
thermal: bandgap: Add TSHUT_CONFIG_ONCE feature

As on OMAP4470 TSHUT config is one time writebale register, we need to ensure
that driver does not try to reconfigure it after it was configured earlier during
boot.
For OMAP4470 GP devices content of tshut config register is not restored
after OFF mode, and it need to be configured manually to prevent spurious TSHUT
interrupt generation.

Change-Id: I6f232d02b534926fd987aaa4b4a87aa522cc8079
Signed-off-by: Ruslan Ruslichenko <ruslan.ruslichenko@ti.com>
thermal: bandgap: Set bandgap to single mode after suspend

After suspend bandgap should be set to single mode to avoid temperature
reading before TSHUT config and other critical registers are configured.
Other way, spurious TSHUT interrupts can be generated as temperature
conversion is done and TSHUT registers are not setup properly yet.
As on some devices continuous mode is default value after suspend and
reset, so we need to set it to single mode manually before enabling
bandgap functional clock.

Change-Id: Ie2a2f3c32ec284c9d40f3fb80e76a54147080540
Signed-off-by: Ruslan Ruslichenko <ruslan.ruslichenko@ti.com>
ARM: omap4plus_pm_min_defconfig: Enable Thermal support

It is not safe to work without thermal framework support, as device
can get overheat and corrupted. Additionally some critical thermal
registers need to be configured (like TSHUT registers) or problem
with OFF mode, warm reset may appear or device even can be damaged
if TSHUT interrupt is not configured and handled properly.

Change-Id: Ia4775e5f5d7411b995fbe76d3999a9a38c0d496a
Signed-off-by: Ruslan Ruslichenko <ruslan.ruslichenko@ti.com>