[NET]: Add a dev_ioctl() fallback to sock_ioctl()

Currently all network protocols need to call dev_ioctl as the default
fallback in their ioctl implementations.  This patch adds a fallback
to dev_ioctl to sock_ioctl if the protocol returned -ENOIOCTLCMD.
This way all the procotol ioctl handlers can be simplified and we don't
need to export dev_ioctl.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c
index e57683d..fbfa967 100644
--- a/net/irda/af_irda.c
+++ b/net/irda/af_irda.c
@@ -1822,7 +1822,7 @@
 		return -EINVAL;
 	default:
 		IRDA_DEBUG(1, "%s(), doing device ioctl!\n", __FUNCTION__);
-		return dev_ioctl(cmd, (void __user *) arg);
+		return -ENOIOCTLCMD;
 	}
 
 	/*NOTREACHED*/