snic: Fix for missing interrupts

- On posting an IO to the firmware, adapter generates an interrupt.
  Due to hardware issues, sometimes the adapter fails to generate
  the interrupt. This behavior skips updating transmit queue-
  counters, which in turn causes the queue full condition. The fix
  addresses the queue full condition.

- The fix also reserves a slot in transmit queue for hba reset.
  when queue full is observed during IO, there will always be room
  to post hba reset command.

Signed-off-by: Narsimhulu Musini <nmusini@cisco.com>
Signed-off-by: Sesidhar Baddela <sebaddel@cisco.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>