[SCSI] libiscsi: make __iscsi_complete_pdu() static

__iscsi_complete_pdu() can now become static.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>