After checking the code, aerl in our session is 0,
so there will be only 1 AER. So currently,
we will only handle 1 AER case.
When the AER event is triggered by real NVMe device owned
by the subsystem, it notifies all sessions belonging to
the subsystem.
Change-Id: Ia80fb0f03e893c20d8dd14afbed8db10db38301c
Signed-off-by: Ziye Yang <ziye.yang@intel.com>