clk: bcm: rpi: Run some clocks at the minimum rate allowed

The core clock and M2MC clocks are shared between some devices (Unicam
controllers and the HVS, and the HDMI controllers, respectively) that
will have various, varying, requirements depending on their current work
load.

Since those loads can require a fairly high clock rate in extreme
conditions (up to ~600MHz), we can end up running those clocks at their
maximum frequency even though we no longer require such a high rate.

Fortunately, those devices don't require an exact rate but a minimum
rate, and all the drivers are using clk_set_min_rate. Thus, we can just
rely on the fact that the clk_request minimum (which is the aggregated
minimum of all the clock users) is what we want at all times.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220225143534.405820-11-maxime@cerno.tech


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