arm64: dts: qcom: Rework X1-based Asus Zenbook A14's displays

arm64: dts: qcom: Rework X1-based Asus Zenbook A14's displays

The laptop comes in two variants:

* UX3407RA, higher end, FHD+ OLED or WOXGA+ OLED panels
* UX3407QA, lower end, FHD+ OLED or FHD+ LCD panels

Even though all three panels work with "edp-panel", unfortunately the
brightness adjustmenet of LCD panel is PWM based, requiring a dedicated
device-tree. Convert "x1p42100-asus-zenbook-a14.dts" into ".dtsi" to
allow for this split, introduce new LCD variant. Leave current variant
without postfix and with the unchanged model name, as some distros
(eg. Ubuntu) rely on this for automatic device-tree detection during
kernel installation/upgrade.

As dedicated device-tree is required, update compatibles of OLED
variants to correct ones. Keep "edp-panel" as fallback, since it is
enough to make the panels work.

While at it moving .dts, .dtsi around, drop 'model' from the top level
x1-asus-zenbook-a14.dtsi as well.

Co-developed-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
Link: https://lore.kernel.org/r/20250927-zenbook-improvements-v3-2-d46c7368dc70@vinarskis.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>