sh: __irq_entry annotate do_IRQ().

This adds an __irq_entry annotation for do_IRQ() so that the IRQ
annotation in the function graph tracer works as advertized. We already
have the IRQENTRY section wired up, so this is just a trivial addition
to actually make use of it.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/kernel/irq.c

@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/kernel_stat.h>
 #include <linux/seq_file.h>
+#include <linux/ftrace.h>
 #include <asm/processor.h>
 #include <asm/machvec.h>
 #include <asm/uaccess.h>
@@ -106,7 +107,7 @@ static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
 #endif
 
-asmlinkage int do_IRQ(unsigned int irq, struct pt_regs *regs)
+asmlinkage __irq_entry int do_IRQ(unsigned int irq, struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
 #ifdef CONFIG_IRQSTACKS