arm64: dts: qcom: x1e80100-romulus: Update firmware nodes

Other x1e machines use _dtbs.elf for these firmwares, which matches the
filenames shipped by Windows.

Fixes: 09d77be5 ("arm64: dts: qcom: Add support for X1-based Surface Laptop 7 devices")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250108124500.44011-1-joel@jms.id.au


Signed-off-by: Bjorn Andersson <andersson@kernel.org>