Enable the bandgap driver for TI SoCs thermal support.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Cc: AnilKumar Ch <anilkumar@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>