leds: flash: leds-qcom-flash: Add PMI8998 support

Add subtype for the Qualcomm PMI8998 PMIC to support it besides the
PM8150 PMIC which has the same registers. Adjust the driver to recognize
both PMIC subtypes as a 3 channel LED driver.

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
Link: https://lore.kernel.org/r/20230507172941.364852-2-me@dylanvanassche.be


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