regulator: arizona-ldo1: Look up a descriptor and pass to the core

Instead of passing a global GPIO number, pass a descriptor looked
up with the standard devm_gpiod_get_optional() call.

We have augmented the GPIO core to look up the regulator special
GPIO "wlf,ldoena" in commit 6a537d48
"gpio: of: Support regulator nonstandard GPIO properties".

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>