[ARC] Add finer details for LLOCK and SCOND

This patch changes the "class" of LLOCK/SCOND from "MEMORY" to
"LLOCK/SCOND" respectively. Moreover, it corrects the "data_size_mode".

These changes are necessary for GDB's atmoic sequence handler.

Signed-off-by: Shahab Vahedi <shahab@synopsys.com>

include/opcode/arc.h

@@ -64,6 +64,7 @@ typedef enum
   JUMP,
   KERNEL,
   LEAVE,
+  LLOCK,
   LOAD,
   LOGICAL,
   LOOP,
@@ -76,6 +77,7 @@ typedef enum
   PMU,
   POP,
   PUSH,
+  SCOND,
   SJLI,
   STORE,
   SUB,