scsi: qla2xxx: target: Fix races with aborting commands

scsi: qla2xxx: target: Fix races with aborting commands

cmd->cmd_lock only protects cmd->aborted, but when deciding how to
process a cmd, it is necessary to consider other factors such as
cmd->state and if the chip has been reset, which are protected by
qpair->qp_lock_ptr.  So replace cmd_lock with qp_lock_ptr, whick makes
it possible to check additional values and make decisions about what to
do without racing with the CTIO handler and other code.

 - Lock cmd->qpair->qp_lock_ptr when aborting a cmd.

 - Eliminate cmd->cmd_lock and change cmd->aborted to a bitfield since
   it is now protected by qp_lock_ptr just like all the other flags.

 - Add another command state QLA_TGT_STATE_DONE to avoid any possible
   races between qlt_abort_cmd() and tgt_ops->free_cmd().

 - Add the cmd->sent_term_exchg flag to indicate if
   qlt_send_term_exchange() has already been called.

 - Export qlt_send_term_exchange() for SCST so that it can be called
   directly instead of trying to make qlt_abort_cmd() work for both TMR
   abort and HW timeout.

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Link: https://patch.msgid.link/2c8d03e4-308b-4d5a-a418-a334be23f815@cybernetics.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>