ARC: Fix pt_orig_r8 access

Syscall restarting fixes made pt_regs->orig_r8 a short word, which was
not reflected in the assembler code - thus could potentially break gdb
debugging.
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>

arch/arc/kernel/entry.S

@@ -496,7 +496,7 @@ tracesys_exit:
 trap_with_param:
 
 	; stop_pc info by gdb needs this info
-	st  orig_r8_IS_BRKPT, [sp, PT_orig_r8]
+	stw orig_r8_IS_BRKPT, [sp, PT_orig_r8]
 
 	mov r0, r12
 	lr  r1, [efa]
@@ -721,7 +721,7 @@ not_exception:
 	; things to what they were, before returning from L2 context
 	;----------------------------------------------------------------
 
-	ld r9, [sp, PT_orig_r8]        ; get orig_r8 to make sure it is
+	ldw  r9, [sp, PT_orig_r8]      ; get orig_r8 to make sure it is
 	brne r9, orig_r8_IS_IRQ2, 149f ; infact a L2 ISR ret path
 
 	ld r9, [sp, PT_status32]       ; get statu32_l2 (saved in pt_regs)