[SCSI] qla4xxx: Populate local CHAP credentials for flash target sessions

If any flash target entry is using CHAP authentication then set
CHAP username and password sysfs params for the corresponding
iscsi sessions.

Signed-off-by: Adheer Chandravanshi <adheer.chandravanshi@qlogic.com>
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>