power: smb5: Evaluate step charging on wdog snarl

Currently, step charging flow is evaluated on every wdog bark irq
trigger. However, the minimum frequency of wdog bark can be 16sec only.
This prevents close approximation of tapered down step-charging
to CC1->CV1->CC2->CV2 mode. Hence, add support to evaluate step charging
flow on every wdog snarl irq, which can trigger at a frequency of 1s,
2s, 4s and 8s, allowing for better approximation.

Further, as per current SW design, wodg snarl IRQ is enabled only if SW
thermal regulation WA is active. To enable wdog snarl irq explicitly for
step charging, its required to specify snarl timer configuration as a dt
parameter. Henceforth, if either wdog snarl timer configuration is defined
as a dt parameter or SW thermal regulation WA is active, then only wdog
snarl irq is enabled, else disabled by default.

Change-Id: I243a23608123ede11c5d497618091cb044203e49
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>