power: supply: sbs-charger: Don't cancel work that is not initialized

This driver can use an interrupt or polling in order get the charger's
status.

When using polling, a delayed work is used.

However, the remove() function unconditionally call
cancel_delayed_work_sync(), even if the delayed work is not used and is not
initialized.

In order to fix it, use devm_delayed_work_autocancel() and remove the now
useless remove() function.

Fixes: feb583e3 ("power: supply: add sbs-charger driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>