pipeline: fix emit instruction for invalid headers

pipeline: fix emit instruction for invalid headers

Fix the emit instruction for the pathological case of all headers to
be emitted being invalid. In this case, the for loop was essentially
skipped and the last emitted header (or an invalid memory location)
getting corrupted by setting its size to 0 through the assignment to
ho->n_bytes right after the for loop.

Fixes: d60dbdc88a3e ("pipeline: create inline functions for emit instruction")
Cc: stable@dpdk.org
Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Signed-off-by: Venkata Suresh Kumar P <venkata.suresh.kumar.p@intel.com>
Signed-off-by: Yogesh Jangra <yogesh.jangra@intel.com>