scsi: qla2xxx: Fix premature command free

When qla2xxx and Target Core gets out of sync during command cleanup, qla2xxx
will not free command until it is out of firmware's hand and Target Core has
called the release on the command.

This patch adds synchronization using cmd_lock and release flag.  If the
release flag is set, then qla2xxx will free up the command using
qlt_free_cmd() otherwise transport_generic_free_cmd() will be responsible for
relase of the command.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>