arm64: dts: qcom: x1e80100-dell-xps13-9345: Enable external DP support

arm64: dts: qcom: x1e80100-dell-xps13-9345: Enable external DP support

Particular laptops comes with two USB Type-C ports, both supporting DP
alt mode. Enable output on both of them. Explicitly list supported
frequencies including HBR3/8.1Gbps for all external DisplayPort(s).

Due to support missing in the USB/DisplayPort combo PHY driver,
the external DisplayPort is limited to 2 lanes.

Derived from:
arm64: dts: qcom: x1e80100-t14s: Add external DP support

Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250226231436.16138-2-alex.vinarskis@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>