regulator/mfd: Support ROHM BD71847 power management IC

BD71847 is reduced version of BD71837. DVS bucks 3 and 4 are
removed as is LDO7. Voltage ranges of some regulators are
expanded.

Add initial support for BD71847 with BD71837 driver.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>