scsi: qla2xxx: Use Correct index for Q-Pair array

For target mode, the default number of Q-Pairs allowed to use is 2. If the
number of Q-Pairs allocated is lower than the default Q-Pairs, then lower
value should be the set as default.

[mkp: typo]

Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>