mfd: dts: hi655x: Add clock binding for the pmic

The hi655x PMIC provides the regulators but also a clock. The latter is
missing in the definition, so extend the documentation to include this as
well.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
[Ulf: Split patch and updated changelog]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>