nat: fix deleting nat ei out interface feature
nat: fix deleting nat ei out interface feature

Type: fix

Set is_add function argument to 0 when deleting interface role.

Change-Id: I6ca88d6511e1c88285e51b3750eb501fde2b341b
Signed-off-by: Alexander Skorichenko <703d2a24b0b1535fae547c8bf104fbdbca084b7c@netgate.com>

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