thermal: ti-bandgap: Add support for temperature sensor

The dra7xx series of SOCs contain a temperature sensor and an
associated analog-to-digital converter (ADC) which produces
an output which is proportional to the SOC temperature.
Add support for this temperature sensor.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index e987c07..c62b82fd 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -605,6 +605,14 @@
 	  enable SPI drivers that are needed for other purposes also, such
 	  as a SPI PMIC.
 
+config SPL_THERMAL
+	bool "Driver support for thermal devices"
+	help
+	  Enable support for temperature-sensing devices. Some SoCs have on-chip
+	  temperature sensors to permit warnings, speed throttling or even
+	  automatic power-off when the temperature gets too high or low. Other
+	  devices may be discrete but connected on a suitable bus.
+
 config SPL_USB_HOST_SUPPORT
 	bool "Support USB host drivers"
 	help