[SCSI] be2iscsi: Return async handle of unknown opcode to free list.

The async handle corresponding to unknown Opcode was not freed
earlier. This code does the fix for that.

Signed-off-by: John Soni Jose <sony.john-n@emulex.com>
Signed-off-by: Jayamohan Kallickal <jayamohan.kallickal@emulex.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>