Don't consider PCIe hot-plug command timeout fatal.
According to my tests and errata to several generations of Intel CPUs,
PCIe hot-plug command completion reporting is not very reliable thing.
At least on my Supermicro X11DPi-NT board I never saw it reported.
Before this change timeout code detached devices and tried to disable
the slot, that in my case resulted in hot-plugged device being detached
just a second after it was successfully detected and attached. This
change removes that, so in case of timeout it just prints the error and
continue operation. Linux does the same.
MFC after: 1 week
Sponsored by: iXsystems, Inc.