backlight: qcom-wled: Add support for WLED5 peripheral that is present on PM8150L PMICs

PM8150L WLED supports the following:
    - Two modulators and each sink can use any of the modulator
    - Multiple CABC selection options from which one can be selected/enabled
    - Multiple brightness width selection (12 bits to 15 bits)

Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>