arm64: dts: qcom: msm8953-xiaomi-daisy: fix backlight

arm64: dts: qcom: msm8953-xiaomi-daisy: fix backlight

The backlight on this device is connected via 3 strings. Currently,
the DT claims only two are present, which results in visible stripes
on the display (since every third backlight string remains unconfigured).

Fix the number of strings to avoid that.

Fixes: 38d779c26395 ("arm64: dts: qcom: msm8953: Add device tree for Xiaomi Mi A2 Lite")
Signed-off-by: Barnabás Czémán <barnabas.czeman@mainlining.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260116-pmi8950-wled-v3-7-e6c93de84079@mainlining.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>