mfd: rk808: Add Rockchip rk817 battery charger support

Add rk817 charger support cell to rk808 mfd driver.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220808173809.11320-3-macroalpha82@gmail.com