MIPS: Return after handling coprocessor 2 exception

Breaking here dropped us to the default code which always sends a SIGILL
to the current process, no matter what the CU2 notifier says.

[Ralf: Currently this only hurts on Cavium and possibly some out of tree
platforms.]
Signed-off-by: NJesper Nilsson <jesper@jni.nu>
To: linux-mips@linux-mips.org
To: linux-kernel@vger.kernel.org
Patchwork: http://patchwork.linux-mips.org/patch/1391/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

@@ -976,7 +976,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 
 	case 2:
 		raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);
-		break;
+		return;
 
 	case 3:
 		break;