re-add VPP buffer override to Vagrant deployment
re-add VPP buffer override to Vagrant deployment

was removed in cfde5fbc, but no replacement provided

Signed-off-by: samuel.elias <d838d617616898a9102a976288eaa6f77e3e0c67@cisco.com>

brecode/vpp,rastislavszabo/vpp,rastislavszabo/vpp,rastislavszabo/vpp,rastislavszabo/vpp,rastislavszabo/vpp,brecode/vpp,rastislavszabo/vpp,brecode/vpp,rastislavszabo/vpp,brecode/vpp,brecode/vpp