Require the user to disable virtual functions before running the device
offline diagnostics.  The offline diagnostics are intended to ensure
basic operation of the device - it is beyond the scope of the diagnostic
test to handle the additional complexity of bringing all the virtual
functions offline and then back online for each test run.

Change-ID: Ic0b854851a09fc85df0c9e82c220e45885457c30
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>