clk: bcm: rpi: Use CCF boundaries instead of rolling our own

The raspberrypi firmware clock driver has a min_rate / max_rate clamping by
storing the info it needs in a private structure.

However, the CCF already provides such a facility, so we can switch to it
to remove the boilerplate.

Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/d4c53dab6de5d5f70743d9c139d0117589530e62.1592210452.git-series.maxime@cerno.tech


Signed-off-by: Stephen Boyd <sboyd@kernel.org>