power: supply: max17040: Use devm_ to automate remove

Two actions were performed during remove - power supply dereg and
delayed work cleanup. Power supply dereg can be handled by using the
devm_ version of the registration function. Work cleanup can be added as
a devm_action.

If probe fails after psy registration it will now be cleaned up
properly.

Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Tested-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>