leds: qti-flash: Update camera flash client interface options

The value of "QUERY_MAX_AVAIL_CURRENT" option in the "leds-qti-flash"
driver is different from the legacy "leds-qpnp-flash" driver.
As a result, the led flash does not work. To fix this issue update
the option values of "leds-qti-flash" to align with the legacy driver.

Also add logic to handle other options "ENABLE_REGULATOR" and
"DISABLE_REGULATOR" to have backward compatibility.

Change-Id: I8213d53c6b19ccc8da74784e3b428b99fcebcbb7
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>