smsc911x: allow using IRQ0

commit 5ef9b80 upstream.

The AlphaProject AP-SH4A-3A/AP-SH4AD-0A SH boards use IRQ0 for their SMSC
LAN911x Ethernet chip, so the networking on them must have been broken by
commit 965b2aa ("net/smsc911x: fix irq resource allocation failure")
which filtered out 0 as well as the negative error codes -- it was kinda
correct at the time, as platform_get_irq() could return 0 on of_irq_get()
failure and on the actual 0 in an IRQ resource.  This issue was fixed by
me (back in 2016!), so we should be able to fix this driver to allow IRQ0
usage again...

When merging this to the stable kernels, make sure you also merge commit
e330b9a ("platform: don't return 0 from platform_get_irq[_byname]()
on error") -- that's my fix to platform_get_irq() for the DT platforms...

Fixes: 965b2aa ("net/smsc911x: fix irq resource allocation failure")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/656036e4-6387-38df-b8a7-6ba683b16e63@omp.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/smsc/smsc911x.c

@@ -2431,7 +2431,7 @@ static int smsc911x_drv_probe(struct platform_device *pdev)
 	if (irq == -EPROBE_DEFER) {
 		retval = -EPROBE_DEFER;
 		goto out_0;
-	} else if (irq <= 0) {
+	} else if (irq < 0) {
 		pr_warn("Could not allocate irq resource\n");
 		retval = -ENODEV;
 		goto out_0;