octeon_ep: fix potential memory leak in octep_device_setup()

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

octeon_ep: fix potential memory leak in octep_device_setup()

When occur unsupported_dev and mbox init errors, it did not free oct->conf

and iounmap() oct->mmio[i].hw_addr. That would trigger memory leak problem.

Add kfree() for oct->conf and iounmap() for oct->mmio[i].hw_addr under

unsupported_dev and mbox init errors to fix the problem.