clk: Use clamp instead of open-coding our own

The code in clk_set_rate_range() will, if the current rate is outside of
the new range, force it to the minimum or maximum.

Since it's running under the condition that the rate is either lower
than the minimum, or higher than the maximum, this is equivalent to
using clamp, while being less readable. Let's switch to using clamp
instead.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220225143534.405820-6-maxime@cerno.tech


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