clk: bd718x7: Support ROHM BD70528 clk block

ROHM BD70528 is an ultra low power PMIC with similar 32K clk as
bd718x7. Only difference (from clk perspective) is register address.
Add support for controlling BD70528 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>