PCI: dwc: ep: Call epc_create() early in dw_pcie_ep_init()

Move devm_pci_epc_create() to the beginning of dw_pcie_ep_init().

devm_pci_epc_create() is generic code that doesn't depend on any DWC
resource, so moving it earlier keeps all the subsequent devicetree-related
code together.

Link: https://lore.kernel.org/r/20250315201548.858189-9-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>