power: smb5: Update USBIN allowance only for USBPD charger

Update USBIN adapter allowance to continuous mode in USBPD voltage
transition, also update CONT_AICL_THRESHOLD based on the minimum USBPD
voltage to prevent USBIN collapse during the transition. After voltage
settled, set USBIN adapter allowance to corresponding fixed voltage
level for fixed PDO and leave it in continuous mode for PPS.

CRs-Fixed: 2451475
Change-Id: Ibff52f31fa9c2a8a99500ed612a2ecabe64e8af8
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>