arm64: dts: qcom: x1-hp-x14: Unify HP Omnibook X14 device tree structure

arm64: dts: qcom: x1-hp-x14: Unify HP Omnibook X14 device tree structure

Extract common elements into a shared .dtsi file for HP Omnibook X14 to
support both Hamoa (x1e*/x1p6*) and Purwa (x1p4*/x1*) variants.
Required because the device trees are not compatible.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
Link: https://lore.kernel.org/r/20250915-hp-x14-x1p-v9-2-fa457ca30ffe@oldschoolsolutions.biz
Signed-off-by: Bjorn Andersson <andersson@kernel.org>