uboot-imx

rockchip: rk3399-puma: defconfig: enable FAN53555 regulator driver

With a driver for the FAN53555 regulator family available, let's
enable it for the RK3399-Q7 (which has two of these devices
on-module).

We enable this for the full U-Boot stage only, as these regulators
provide a suitable default voltage and supply non-critical (i.e.
for booting up) power rails only.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>