power: supply: cros-ec-usbpd-charger: Fix host events

There's a bug on ACPI platforms where host events from the ECPD ACPI
device never make their way to the cros-ec-usbpd-charger driver. This
makes it so the only time the charger driver updates its state is when
user space accesses its sysfs attributes.

Now that these events have been unified into a single notifier chain on
both ACPI and non-ACPI platforms, update the charger driver to use this
new notifier.

Reviewed-by: Benson Leung <bleung@chromium.org>
Co-Developed-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Jon Flatley <jflat@chromium.org>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>