examples/ip_pipeline: fix parsing of pass-through pipeline

examples/ip_pipeline: fix parsing of pass-through pipeline

This patch fixes the configuration file parsing error when load balancing
function is enabled in pass-through pipeline.

error log:
pipeline> [APP] Initializing PIPELINE1 ...
[PIPELINE1] Pass-through
Parse error in section "PIPELINE1": entry "lb" has invalid value ("hash")

Fixes: cbe82f6cfb0a ("examples/ip_pipeline: add swap action in pass-through")
Cc: stable@dpdk.org
Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>