libmemif: fix chained buffer flag
libmemif: fix chained buffer flag

fixes issue: MEMIF_DESC_FLAG_NEXT persisted when enqueueing
stored buffers

Type: fix

Change-Id: I9e973ed6e0339612fe1dd3e3bd80ed7c05093791
Signed-off-by: Jakub Grajciar <80f619e109c6efd382b3a6accd36cbd33d9669a2@cisco.com>

FDio/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,vpp-dev/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp