clk: clk-max77686: Clean clkdev lookup leak and use devm

clk-max77686 never clean clkdev lookup at remove. This can cause
oops if clk-max77686 is removed and inserted again. Fix leak by
using new devm clkdev lookup registration. Simplify also error
path by using new devm_of_clk_add_hw_provider.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>