dt-bindings: mfd: update TI tps6105x chip bindings

The driver has been extended to optionally get its operational
mode, regulator init data and LED naming from the devicetree.

Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>