tools/mm: free the allocated memory

The comm_str memory needs to be freed if the search_pattern function call
fails in get_comm

[[e-mail]: fix whitespace]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Liu Jing <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/mm/page_owner_sort.c

···
 	if (errno != 0) {
 		if (debug_on)
 			fprintf(stderr, "wrong comm in follow buf:\n%s\n", buf);
+		free(comm_str);
 		return NULL;
 	}