mpls: fix adjacencies walk in case of restack
mpls: fix adjacencies walk in case of restack

Adjacencies are only defined for IPv4 and IPv6.

Type: fix
Fixes: 20aec3db441074ee5a861a40d6e02fad2f3dcb37

Change-Id: I19b2b7f6958da49f41c6eabc9f248840769acbbb
Signed-off-by: Benoît Ganne <38aad8ffcfa407b890d258e568f161530f66882d@cisco.com>

chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp