power: isl9519q: Add pm8921 external-charger support

The isl9519q interface with the pm8921 via external-charger registration.
The pm8921 notifies the isl9519q to start/stop charging.
This way the isl9519q driver doesn't need to:
1. Monitor the charge current for end-of-charging detection.
2. Get interrupt from isl9519q HW.
3. Check n_valid_gpio for DC Inserted validity.

Change-Id: Ia0472440010fe1582a5aa8b557c9e4ab17e1a657
Signed-off-by: Amir Samuelov <amirs@codeaurora.org>
2 files changed