MIPS: Use force_sig when handling address errors.

When init is started it is SIGNAL_UNKILLABLE.  If it were to get an
address error, we would try to send it SIGBUS, but it would be ignored
and the faulting instruction restarted.  This results in an endless
loop.

We need to use force_sig() instead so it will actually die and give us
some useful information.
Reported-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/unaligned.c

@@ -482,19 +482,19 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 		return;
 
 	die_if_kernel("Unhandled kernel unaligned access", regs);
-	send_sig(SIGSEGV, current, 1);
+	force_sig(SIGSEGV, current);
 
 	return;
 
 sigbus:
 	die_if_kernel("Unhandled kernel unaligned access", regs);
-	send_sig(SIGBUS, current, 1);
+	force_sig(SIGBUS, current);
 
 	return;
 
 sigill:
 	die_if_kernel("Unhandled kernel unaligned access or invalid instruction", regs);
-	send_sig(SIGILL, current, 1);
+	force_sig(SIGILL, current);
 }
 
 asmlinkage void do_ade(struct pt_regs *regs)