vpp_papi: Fix format_vl_api_address_t under python3.
vpp_papi: Fix format_vl_api_address_t under python3.

Under PY3, inet_pton returns OSError, not socket.error.

Type: fix

Change-Id: Id270a684c0ab124cbe1ddcb7123e14e85af844b8
Signed-off-by: Paul Vinciguerra <b92f79aabe4c9c18085c7347110a52af0898a0ef@vinciconsulting.com>

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