The driver now sets an appropriate default for WLED4 (and WLED5) just
like WLED3 making this linear array from 0-3 redundant.  In addition the
driver is now able to parse arrays of variable length solving the "all
four strings *have to* be defined" comment.

Besides the driver will now warn when both properties are specified to
prevent ambiguity: the length of the array is enough to imply a set
number of strings.
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/20211007213400.258371-12-marijn.suijten@somainline.org