mfd: da9052: Fix volatile register definition ommissions

Three of the PMIC registers have some bits that are changed
autonomously by the PMIC itself (some time) after being set
by some component driver of the DA9052 PMIC and hence they
need to be marked as volatile so that the regmap API will
not cache their values.

Acked-by: David Dajun Chen <david.chen@diasemi.com>
Signed-off-by: Anthony Olech <anthony.olech.opensource@diasemi.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>