net: stmmac: Fix unbalanced IRQ wake disable warning on single irq case

Commit a23aa04 ("net: stmmac: ethtool: Fixed calltrace caused by
unbalanced disable_irq_wake calls") introduced checks to prevent
unbalanced enable and disable IRQ wake calls. However it only
initialized the auxiliary variable on one of the paths,
stmmac_request_irq_multi_msi(), missing the other,
stmmac_request_irq_single().

Add the same initialization on stmmac_request_irq_single() to prevent
"Unbalanced IRQ <x> wake disable" warnings from being printed the first
time disable_irq_wake() is called on platforms that run on that code
path.

Fixes: a23aa04 ("net: stmmac: ethtool: Fixed calltrace caused by unbalanced disable_irq_wake calls")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241101-stmmac-unbalanced-wake-single-fix-v1-1-5952524c97f0@collabora.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: nfraprado

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

@@ -3780,6 +3780,7 @@ static int stmmac_request_irq_single(struct net_device *dev)
 	/* Request the Wake IRQ in case of another line
 	 * is used for WoL
 	 */
+	priv->wol_irq_disabled = true;
 	if (priv->wol_irq > 0 && priv->wol_irq != dev->irq) {
 		ret = request_irq(priv->wol_irq, stmmac_interrupt,
 				  IRQF_SHARED, dev->name, dev);