clk: bd718x7: Support ROHM BD71828 clk block

BD71828GW is a single-chip power management IC for battery-powered portable
devices. Add support for controlling BD71828 clk using bd718x7 driver.

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