power: qpnp-smbcharger: add support for configuring OTG pulse skip

In OTG mode, when there is no load and flash is being enabled, it
causes a voltage dip at USB_IN and cause OTG device not to work.
To avoid such scenarios, OTG pulse skip should be enabled before
the flash is enabled. Also, before the flash is disabled, OTG
pulse skip should be disabled. Add support for this through the
power supply property flash_active.

CRs-Fixed: 793295
Change-Id: Ieb81fe039ce3b98ddc6942531a751cc287ab0a71
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>