arm64: dts: qcom: Move WLED num-strings from pmi8994 to sony-xperia-tone

The number of WLED strings used by a certain platform depend on the
panel connected to that board and may not be the same for every user of
pmi8994.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-By: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211007213400.258371-13-marijn.suijten@somainline.org