[SOFTIRQ]: Remove do_softirq() symbol export.

As noted by Christoph Hellwig, pktgen was the only user so
it can now be removed.

[ Add missing cases caught by Adrian Bunk. -DaveM ]

Signed-off-by: Robert Olsson <robert.olsson@its.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sh/kernel/irq.c

@@ -245,7 +245,6 @@ asmlinkage void do_softirq(void)
 
 	local_irq_restore(flags);
 }
-EXPORT_SYMBOL(do_softirq);
 #endif
 
 void __init init_IRQ(void)