pmic: pca9450: Make warm reset on WDOG_B assertion

pmic: pca9450: Make warm reset on WDOG_B assertion

The default configuration of the PMIC behavior makes the PMIC
power cycle most regulators on WDOG_B assertion. This power
cycling causes the memory contents of OCRAM to be lost.
Some systems neeeds some memory that survives reset and
reboot, therefore this patch is created.

The implementation is taken almost verbatim from Linux commit
2364a64d0673f ("regulator: pca9450: Make warm reset on WDOG_B assertion")

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>