uboot-phytec

rockchip: Add common reset cause

Add cpu reset cause in common cpu-info file.

This would help to print the reset cause for
various resets.

Right now it support rk3288, rk3399. rest of rockchip
platforms doesn't have reset cause support ye but this
code is more feasible to extend the same.

Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>