leds: qpnp-wled: Improve auto calibration algorithm

If CABC is enabled and auto calibration is attempted, then OVP
fault can be seen even with a valid sink configuration and a
brightness level greater than or equal to 0.4 % dimming. This is
because of the modulation done through CABC pin which if low
enough can cause the brightness level to still go further down.

Fix this by disabling CABC on all sinks before running auto
calibration and re-enable it if the feature is enabled. Also,
modify the auto calibration brightness level to 200 so that the
load increase on WLED_VOUT can bring the voltage below OVP
threshold quick enough on a valid sink configuration.

Finally, disable WLED module before switching the sink
configuration and enable it after configuring sinks.

CRs-Fixed: 2125217
Change-Id: I570dc9eba540cd96328afd7c68f4643a112c4962
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>