ARC: Fix the typo in event identifier flags used by ptrace

orig_r8_IS_EXCPN and orig_r8_IS_BRKPT were same values due to a
copy/paste error. Although it looks bad and is wrong, it really doesn't
affect gdb working.

orig_r8_IS_BRKPT is the one relevant to debugging (breakpoints), since
it is used to provide EFA vs. ERET to a ptrace "stop_pc" request.

So when gdb has inserted a breakpoint, orig_r8_IS_BRKPT is already set,
and anything else (i.e. orig_r8_IS_EXCPN) becoming same as it, really
doesn't hurt gdb. The corollary case, could be nasty but nobody uses the
ptrace "stop_pc" request in that case

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index b9d875a..91eeab8 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -452,7 +452,7 @@
 	; using ERET won't work since next-PC has already committed
 	lr  r12, [efa]
 	GET_CURR_TASK_FIELD_PTR   TASK_THREAD, r11
-	st  r12, [r11, THREAD_FAULT_ADDR]
+	st  r12, [r11, THREAD_FAULT_ADDR]	; thread.fault_address
 
 	; PRE Sys Call Ptrace hook
 	mov r0, sp			; pt_regs needed