clk: meson: g12: use devm variant to register notifiers

Until now, nothing was done to unregister the dvfs clock notifiers of the
Amlogic g12 SoC family. This is not great but this driver was not really
expected to be unloaded. With the ongoing effort to build everything as
module for this platform, this needs to be cleanly handled.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20201021163847.595189-3-jbrunet@baylibre.com


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