MIPS: add nmi_enter() + nmi_exit() to nmi_exception_handler()

We need to enter NMI context when NMI interrupt fires.
Signed-off-by: Petri Gynther <pgynther@google.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11323/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

@@ -1856,12 +1856,14 @@ void __noreturn nmi_exception_handler(struct pt_regs *regs)
 {
 	char str[100];
 
+	nmi_enter();
 	raw_notifier_call_chain(&nmi_chain, 0, regs);
 	bust_spinlocks(1);
 	snprintf(str, 100, "CPU%d NMI taken, CP0_EPC=%lx\n",
 		 smp_processor_id(), regs->cp0_epc);
 	regs->cp0_epc = read_c0_errorepc();
 	die(str, regs);
+	nmi_exit();
 }
 
 #define VECTORSPACING 0x100	/* for EI/VI mode */