arm64: dts: qcom: sc8280xp-x13s: Update firmware location

The firmware location in linux-firmware has been changed to include the
SoC name. So use the updated location in Thinkpad devicetree.

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220914073922.7145-1-manivannan.sadhasivam@linaro.org