power: add SMB1390 charge pump driver

SMB1390 is a charge pump PMIC and is used as a companion charger to the
primary charging PMIC. This driver implements all of the required
functionality to be used as a parallel charger.

CRs-Fixed: 2200333

Change-Id: I9e58773241a2b9865067ac563ca96a75afc34611
Signed-off-by: Nicholas Troast <ntroast@codeaurora.org>
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>