arm64: dts: qcom: sdm845-shift-axolotl: Enable pmi9889 LPG LED

arm64: dts: qcom: sdm845-shift-axolotl: Enable pmi9889 LPG LED

Enables the RGB notification LED on the SHIFT 6mq (sdm845-shift-axolotl)
with the Qualcomm Light Pulse Generator bindings by Bjorn Andersson [1].
Patches are merged in for-next branch of linux-leds.
Tested these changes on the SHIFT 6mq.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds.git/commit/?h=for-next&id=a8e53db46f19f67be6a26488aafb7d10c78e33bd

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
Reviewed-by: Alexander Martinz <amartinz@shiftphones.com>
Tested-by: Alexander Martinz <amartinz@shiftphones.com>
Tested-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Caleb Connolly <caleb@connolly.tech>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220512054439.13971-1-me@dylanvanassche.be