scsi: qla2xxx: Reset the FCF_ASYNC_{SENT|ACTIVE} flags

Driver maintains state machine for processing and completing switch
commands. This patch resets FCF_ASYNC_{SENT|ACTIVE} flag to indicate if the
previous command is active or sent, in order for next GPSC command to
advance the state machine.

[mkp: commit desc typo]

Signed-off-by: Giridhar Malavali <gmalavali@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>