platform: don't return 0 from platform_get_irq[_byname]() on error

commit e330b9a6 upstream.

of_irq_get[_byname]() return 0 iff  irq_create_of_mapping() call fails.
Returning both  error code and 0 on failure is a sign of a misdesigned API,
it makes the failure check unnecessarily complex and error prone. We should
rely  on the platform IRQ resource in this case, not return 0,  especially
as 0 can be  a valid  IRQ resource too...

Fixes: aff008ad ("platform_get_irq: Revert to platform_get_resource if of_irq_get fails")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/base/platform.c

@@ -93,7 +93,7 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
 		int ret;
 
 		ret = of_irq_get(dev->dev.of_node, num);
-		if (ret >= 0 || ret == -EPROBE_DEFER)
+		if (ret > 0 || ret == -EPROBE_DEFER)
 			return ret;
 	}
 
@@ -142,7 +142,7 @@ int platform_get_irq_byname(struct platform_device *dev, const char *name)
 		int ret;
 
 		ret = of_irq_get_byname(dev->dev.of_node, name);
-		if (ret >= 0 || ret == -EPROBE_DEFER)
+		if (ret > 0 || ret == -EPROBE_DEFER)
 			return ret;
 	}