net: stmmac: initialize the reset delay array

Commit ce4ab73a ("net: stmmac: drop the reset delays from struct
stmmac_mdio_bus_data") moved the reset delay array from struct
stmmac_mdio_bus_data to a stack variable.
The values from the array inside struct stmmac_mdio_bus_data were
previously initialized to 0 because the struct was allocated using
devm_kzalloc(). The array on the stack has to be initialized
explicitly, else we might be reading garbage values.

Initialize all reset delays to 0 to ensure that the values are 0 if the
"snps,reset-delays-us" property is not defined.
This fixes booting at least two boards (MIPS pistachio marduk and ARM
sun8i H2+ Orange Pi Zero). These are hanging during boot when
initializing the stmmac Ethernet controller (as found by Kernel CI).
Both have in common that they don't define the "snps,reset-delays-us"
property.

Fixes: ce4ab73a ("net: stmmac: drop the reset delays from struct stmmac_mdio_bus_data")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c

@@ -241,7 +241,7 @@ int stmmac_mdio_reset(struct mii_bus *bus)
 #ifdef CONFIG_OF
 	if (priv->device->of_node) {
 		struct gpio_desc *reset_gpio;
-		u32 delays[3];
+		u32 delays[3] = { 0, 0, 0 };
 		int ret;
 
 		reset_gpio = devm_gpiod_get_optional(priv->device,