scsi: qla2xxx: Fix comment in MODULE_PARM_DESC in qla2xxx

Default value of ql2xasynctmfenable for qla2xxx driver was set to 1 in
commit 043dc1d7 ("scsi: qla2xxx: Enable Async TMF processing") but
comment in MODULE_PARAM_DESC was not modified.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>