mfd: twl4030-power: Add support for board specific configuration

With the recommended twl4030 configuration added, we can now add
board specific changes as modifications to the recommended
configuration.

Note that the data is private to this driver, and the data must
always have a NULL resource in the sentinel.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>