backlight: qcom-wled: Remove unnecessary 4th default string in WLED3

backlight: qcom-wled: Remove unnecessary 4th default string in WLED3

The previous commit improves num_strings parsing to not go over the
maximum of 3 strings for WLED3 anymore.  Likewise this default index for
a hypothetical 4th string is invalid and could access registers that are
not mapped to the desired purpose.
Removing this value gets rid of undesired confusion and avoids the
possibility of accessing registers at this offset even if the 4th array
element is used by accident.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211115203459.1634079-7-marijn.suijten@somainline.org