regulator: bd71837: copy the bd71837 pmic driver from NXP imx u-boot

https://source.codeaurora.org/external/imx/uboot-imx

cherry picked, styled and merged commits:
- MLK-18387 pmic: Add pmic driver for BD71837: e9a3bec2e95a
- MLK-18590 pmic: bd71837: Change to use new fdt API: acdc5c297a96

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
4 files changed