net: phy: micrel: Do not use kszphy_suspend/resume for KSZ8061

Since commit f1131b9 ("net: phy: micrel: use
kszphy_suspend()/kszphy_resume for irq aware devices") the following
NULL pointer dereference is observed on a board with KSZ8061:

 # udhcpc -i eth0
udhcpc: started, v1.35.0
8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000008
pgd = f73cef4e
[00000008] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
Modules linked in:
CPU: 0 PID: 196 Comm: ifconfig Not tainted 5.15.37-dirty torvalds#94
Hardware name: Freescale i.MX6 SoloX (Device Tree)
PC is at kszphy_config_reset+0x10/0x114
LR is at kszphy_resume+0x24/0x64
...

The KSZ8061 phy_driver structure does not have the .probe/..driver_data
fields, which means that priv is not allocated.

This causes the NULL pointer dereference inside kszphy_config_reset().

Fix the problem by using the generic suspend/resume functions as before.

Another alternative would be to provide the .probe and .driver_data
information into the structure, but to be on the safe side, let's
just restore Ethernet functionality by using the generic suspend/resume.

Cc: [email protected]
Fixes: f1131b9 ("net: phy: micrel: use kszphy_suspend()/kszphy_resume for irq aware devices")
Signed-off-by: Fabio Estevam <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

drivers/net/phy/micrel.c

@@ -2782,8 +2782,8 @@ static struct phy_driver ksphy_driver[] = {
 	.config_init	= ksz8061_config_init,
 	.config_intr	= kszphy_config_intr,
 	.handle_interrupt = kszphy_handle_interrupt,
-	.suspend	= kszphy_suspend,
-	.resume		= kszphy_resume,
+	.suspend	= genphy_suspend,
+	.resume		= genphy_resume,
 }, {
 	.phy_id		= PHY_ID_KSZ9021,
 	.phy_id_mask	= 0x000ffffe,