net: stmmac: dwmac-rk: Fix ethernet on rk3399 based devices

Commit 2d26f6e3 ("net: stmmac: dwmac-rk: fix unbalanced pm_runtime_enable warnings")
while getting rid of a runtime PM warning ended up breaking ethernet
on rk3399 based devices. By dropping an extra reference to the device,
the commit ends up enabling suspend / resume of the ethernet device -
which appears to be broken.

While the issue with runtime pm is being investigated, partially
revert commit 2d26f6e3 to restore the network on rk3399.

Fixes: 2d26f6e3 ("net: stmmac: dwmac-rk: fix unbalanced pm_runtime_enable warnings")
Suggested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Punit Agrawal <punitagrawal@gmail.com>
Cc: Michael Riesch <michael.riesch@wolfvision.net>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20210929135049.3426058-1-punitagrawal@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c

@@ -21,6 +21,7 @@
 #include <linux/delay.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
+#include <linux/pm_runtime.h>
 
 #include "stmmac_platform.h"
 
@@ -1528,6 +1529,8 @@ static int rk_gmac_powerup(struct rk_priv_data *bsp_priv)
 		return ret;
 	}
 
+	pm_runtime_get_sync(dev);
+
 	if (bsp_priv->integrated_phy)
 		rk_gmac_integrated_phy_powerup(bsp_priv);
 
@@ -1539,6 +1542,8 @@ static void rk_gmac_powerdown(struct rk_priv_data *gmac)
 	if (gmac->integrated_phy)
 		rk_gmac_integrated_phy_powerdown(gmac);
 
+	pm_runtime_put_sync(&gmac->pdev->dev);
+
 	phy_power_on(gmac, false);
 	gmac_clk_enable(gmac, false);
 }