regulator: max77686: Document gpio properties
regulator: max77686: Document gpio properties

Document usage of maxim,ena-gpios properties which turn on external/GPIO
control over regulator.

Signed-off-by: Krzysztof Kozlowski <1a8531307367602b8284517edb33d53d54e5ce8e@samsung.com>
Signed-off-by: Mark Brown <b51b9a92386687a9ac927cebfa0f978adeb8cea5@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs