mfd: rn5t618: Add Ricoh RC5T619 PMIC support

The Ricoh RN5T567 is from the same family as the Ricoh RN5T618 is,
the differences are:

+ DCDC4/DCDC5
+ LDO7-10
+ Slightly different output voltage/currents
+ 32kHz Output
+ RTC
+ USB Charger detection

Signed-off-by: Pierre-Hugues Husson <phh@phh.me>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>