arm64: dts: qcom: sdm845-xiaomi-beryllium: enable qcom wled backlight and link to panel

Xiaomi Poco F1 uses the QCOM WLED driver for backlight control.
Enable and link it to the panel to use it.

Signed-off-by: Joel Selvaraj <jo@jsfamily.in>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/BY5PR02MB70092607CD7CDD8CF8BCD464D9E09@BY5PR02MB7009.namprd02.prod.outlook.com