clk: add devm variant of clk_notifier_register

Add a memory managed variant of clk_notifier_register() to make life easier
on clock consumers using notifiers

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20201021163847.595189-2-jbrunet@baylibre.com


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