net: fec: allow to build without PAGE_POOL_STATS

Commit 6970ef2 ("net: fec: add xdp and page pool statistics") selected
CONFIG_PAGE_POOL_STATS from the FEC driver symbol, making it impossible
to build without the page pool statistics when this driver is enabled. The
help text of those statistics mentions increased overhead. Allow the user
to choose between usefulness of the statistics and the added overhead.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230616191832.2944130-1-l.stach@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/Kconfig

@@ -29,7 +29,7 @@ config FEC
 	select CRC32
 	select PHYLIB
 	select PAGE_POOL
-	select PAGE_POOL_STATS
+	imply PAGE_POOL_STATS
 	imply NET_SELFTESTS
 	help
 	  Say Y here if you want to use the built-in 10/100 Fast ethernet

drivers/net/ethernet/freescale/fec_main.c

@@ -2789,6 +2789,7 @@ static void fec_enet_get_xdp_stats(struct fec_enet_private *fep, u64 *data)
 
 static void fec_enet_page_pool_stats(struct fec_enet_private *fep, u64 *data)
 {
+#ifdef CONFIG_PAGE_POOL_STATS
 	struct page_pool_stats stats = {};
 	struct fec_enet_priv_rx_q *rxq;
 	int i;
@@ -2803,6 +2804,7 @@ static void fec_enet_page_pool_stats(struct fec_enet_private *fep, u64 *data)
 	}
 
 	page_pool_ethtool_stats_get(data, &stats);
+#endif
 }
 
 static void fec_enet_get_ethtool_stats(struct net_device *dev,