arm64: dts: qcom: pm6150l: add spmi-flash-led node

Add a node describing the flash block found on pm6150l.

Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221209-fp4-pm6150l-flash-v1-2-531521eb2a72@fairphone.com