leds: flash: leds-qcom-flash: Disable LED when changing brightness

The Qualcomm PMI8998 PMIC requires the LED to be disabled when configuring
the brightness. Always disable the LED when setting the brightness and
re-enable it afterwards.

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
Link: https://lore.kernel.org/r/20230507172941.364852-3-me@dylanvanassche.be


Signed-off-by: Lee Jones <lee@kernel.org>