pipeline: fix double free for table stats

[ upstream commit 2d9e10932d535ea553081b489a25f6fce7ec7996 ]

The pointer to the table statistics data structure needs to be set
to NULL after free inside the table_build_free(), as this function is
called from multiple places, leading to double memory free error.

Similar fix for the learner_build_free() function.

Fixes: 742b0a5 ("pipeline: add table statistics to SWX")
Fixes: 4f59d37 ("pipeline: support learner tables")

Signed-off-by: Kamalakannan R <kamalakannan.r@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>

lib/pipeline/rte_swx_pipeline.c

@@ -7635,6 +7635,7 @@ table_build_free(struct rte_swx_pipeline *p)
 			free(p->table_stats[i].n_pkts_action);
 
 		free(p->table_stats);
+		p->table_stats = NULL;
 	}
 }
 
@@ -8443,6 +8444,7 @@ learner_build_free(struct rte_swx_pipeline *p)
 			free(p->learner_stats[i].n_pkts_action);
 
 		free(p->learner_stats);
+		p->learner_stats = NULL;
 	}
 }