MIPS: die() does not call die notifier chain

The MIPS implementation of die() forgets to call notify_die() and thus notifiers
registered via register_die_notifier() are not called.  This results in kgdb not
being activated on exceptions.

The only subtlety is that notify_die declares its regs argument w/o const, so
the const had to be removed from mips die() as well.

[Ralf: Fixed build error for SGI IP22 and IP28 platforms.]

Signed-off-by: Yury Polyanskiy <ypolyans@princeton.edu>
Cc: linux-mips@linux-mips.org
Patchworks: http://patchwork.linux-mips.org/patch/1142/
Acked-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

---
diff --git a/arch/mips/sgi-ip22/ip28-berr.c b/arch/mips/sgi-ip22/ip28-berr.c
index 30e12e2..88c684e 100644
--- a/arch/mips/sgi-ip22/ip28-berr.c
+++ b/arch/mips/sgi-ip22/ip28-berr.c
@@ -453,7 +453,7 @@
 
 void ip22_be_interrupt(int irq)
 {
-	const struct pt_regs *regs = get_irq_regs();
+	struct pt_regs *regs = get_irq_regs();
 
 	count_be_interrupt++;