[MIPS] lockdep: fix TRACE_IRQFLAGS_SUPPORT

In handle_sys and its variants, we must reload some registers which
might be clobbered by trace_hardirqs_on().
Also we must make sure trace_hardirqs_on() called in kernel level (not
exception level).

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/scall64-o32.S

@@ -28,7 +28,7 @@
 NESTED(handle_sys, PT_SIZE, sp)
 	.set	noat
 	SAVE_SOME
-	TRACE_IRQS_ON
+	TRACE_IRQS_ON_RELOAD
 	STI
 	.set	at
 	ld	t1, PT_EPC(sp)		# skip syscall on return