PCI: dwc: Deallocate EPC memory on dw_pcie_ep_init() errors

In the Linux kernel, the following vulnerability has been resolved:

PCI: dwc: Deallocate EPC memory on dw_pcie_ep_init() errors

If dw_pcie_ep_init() fails to perform any action after the EPC memory is

initialized and the MSI memory region is allocated, the latter parts won't

be undone thus causing a memory leak. Add a cleanup-on-error path to fix

these leaks.

[bhelgaas: commit log]