interface: interface dump API check validity of sw_if_index
interface: interface dump API check validity of sw_if_index

Type: fix
Fixes: 6407ba56

Change-Id: I6d3ce68962986921e04aa00c989d8afa157ebcb8
Signed-off-by: Neale Ranns <b9c0e9ef0223633bc2f318425f615cf5840a0be7@cisco.com>

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