arm64: dts: qcom: x1-vivobook-s15: create a common dtsi for Hamoa and Purwa variants

arm64: dts: qcom: x1-vivobook-s15: create a common dtsi for Hamoa and Purwa variants

The Asus VivoBook S15 S5507QA is sold with x1e-78-100 and x1p-42-100 SKUs.
Put the common part into one dtsi file to be included for model-specific dts.
Include the common part in the existing Vivobook S15 device tree.

Tested-by: Colin K. Williams <colin@li-nk.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
Tested-by: Maud Spierings <maud_spierings@hotmail.com>
Link: https://lore.kernel.org/r/20260214-b4-vivobook-v3-3-3c88065bbf77@oldschoolsolutions.biz
Signed-off-by: Bjorn Andersson <andersson@kernel.org>