[U-Boot] test.py failure in test_ut[ut_dm_pci_ep_base]

[Stephen Warren]

Running test.py on sandbox now fails test_ut[ut_dm_pci_ep_base] with:

=> ut dm pci_ep_base
Test: dm_test_pci_ep_base: pci_ep.c
[Errno 5] Input/output error

I believe that last line is printed by the test harness; presumably the 
sandbox process crashed, but I haven't checked that.

I imagine this was introduced by commit "test: pci_ep: add basic pci_ep 
tests".

I do see later commit "test: Disable pci_ep test for now" by Tom, but 
for some reason the test is still running after that; my test system 
last built a9a3a37f92b0 and there's still a failure.