ARM: dts: omap: omap4-epson-embt2ws: define GPIO regulators

To properly have things running after cold boot, define
GPIO regulators. Naming is based on board file.

In the vendor kernel they are enabled in a function
called bt2ws_dcdc_init() if the system is not booted just
to charge the battery.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20241010122957.85164-2-andreas@kemnade.info


Signed-off-by: Kevin Hilman <khilman@baylibre.com>