Currently if SSR happens and at the same time if driver gets
del virtual interface which is a vdev transition, it bloks
this vdev transition and queues into dsc queue assuming that
it will execute once SSR completes.
There is an issue with above assumption,
del virtual interface comes with rtnl lock held which may lead
for other processes to misbehave which are waiting for rtnl lock.
in current case kernel is waiting for rtnl lock to send
shutdown to driver as part of the SSR and this rtnl lock is held
by del virtual interface which is waiting inside dsc queue for
SSR to complete, this leads to the deadlock.
To address above issue, do not insert the vdev transintion in
dsc queue in case of SSR and return the failure instead.
Change-Id: I19c897d68086d885f340d35c686badb70601076a
CRs-Fixed: 2730903
4b436bcbc3