[SCSI] qla4xxx: overflow in qla4xxx_set_chap_entry()

We should cap the size of memcpy() because it comes from the network
and can't be trusted.

Fixes: 26ffd7b4 ('[SCSI] qla4xxx: Add support to set CHAP entries')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>