ARM: dts: omap3: Include missing bandgap data for ti-soc-thermal driver

Driver for omap3 with documentation is there since v4.4-rc1.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Pavel Machek <pavel@ucw.cz>
[tony@atomide.com: added thermal-sensor-cells as suggested by Roger]
Signed-off-by: Tony Lindgren <tony@atomide.com>