dt-bindings: PCI: Convert v3,v360epc-pci to DT schema

dt-bindings: PCI: Convert v3,v360epc-pci to DT schema

Convert the v3,v360epc-pci binding to DT schema format.

Add "clocks" which was not documented and is required. Drop "syscon"
which was documented, but is not used.

Drop the "v3,v360epc-pci" compatible by itself as this device is only
used on the Arm Integrator/AP and not likely going to be used anywhere
else at this point.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patch.msgid.link/20250505220139.2202164-1-robh@kernel.org