lsi: Purge message queue on reset

Declare the input message queue empty and initialize the related state
machine properly on controller reset. This fixes unrecoverable errors
when the controller was reset during ongoing requests.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
