arm64: dts: qcom: pmi8994: Fix "eternal"->"external" typo in WLED node

The property is named "qcom,external-pfet", as found by
dt_binding_check:

    'qcom,eternal-pfet' does not match any of the regexes

Fixes: 37aa540c ("arm64: dts: qcom: pmi8994: Add WLED node")
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/20211007213400.258371-11-marijn.suijten@somainline.org