tools: ynl: fix build of the page-pool sample

The name of the "destroyed" field in the reply was not changed
in the sample after we started calling it "detach_time".

page-pool.c: In function ‘main’:
page-pool.c:84:33: error: ‘struct <anonymous>’ has no member named ‘destroyed’
   84 |                 if (pp->_present.destroyed)
      |                                 ^

Fixes: 637567e ("tools: ynl: add sample for getting page-pool information")
Link: https://lore.kernel.org/r/20231129193622.2912353-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/samples/page-pool.c

@@ -81,7 +81,7 @@ int main(int argc, char **argv)
 		struct stat *s = find_ifc(&a, pp->ifindex);
 
 		count(s, 1, pp);
-		if (pp->_present.destroyed)
+		if (pp->_present.detach_time)
 			count(s, 0, pp);
 	}
 	netdev_page_pool_get_list_free(pools);