virtio: add the checks for descriptors chain len
virtio: add the checks for descriptors chain len

Type: fix

virtio uses indirect descriptors for chain buffers.
indirect descriptor chain is mapped on a vlib_buffer_t.
Single descriptor is 16 bytes and vlib_buffer_t has
2048 bytes space. So maximum long chain can have
128 (=2048/16) indirect descriptors.

This patch adds check to make sure descriptors chain
len should not exceed 128.

Signed-off-by: Mohsin Kazmi <3be96aed1fe21f963e790909e1d3a8e57ce776f2@cisco.com>
Change-Id: I060cfb7709568f42c9b5634527172690ce66a1a3

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