Revert "ARCv2: STAR 9000837815 workaround hardware exclusive transactions livelock"

Extended testing of quad core configuration revealed that this fix was
insufficient. Specifically LTP open posix shm_op/23-1 would cause the
hardware livelock in llock/scond loop in update_cpu_load_active()

So remove this and make way for a proper workaround

This reverts commit a5c8b52a.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/atomic.h

@@ -23,21 +23,13 @@
 
 #define atomic_set(v, i) (((v)->counter) = (i))
 
-#ifdef CONFIG_ISA_ARCV2
-#define PREFETCHW	"	prefetchw   [%1]	\n"
-#else
-#define PREFETCHW
-#endif
-
 #define ATOMIC_OP(op, c_op, asm_op)					\
 static inline void atomic_##op(int i, atomic_t *v)			\
 {									\
 	unsigned int temp;						\
 									\
 	__asm__ __volatile__(						\
-	"1:				\n"				\
-	PREFETCHW							\
-	"	llock   %0, [%1]	\n"				\
+	"1:	llock   %0, [%1]	\n"				\
 	"	" #asm_op " %0, %0, %2	\n"				\
 	"	scond   %0, [%1]	\n"				\
 	"	bnz     1b		\n"				\
@@ -58,9 +50,7 @@ static inline int atomic_##op##_return(int i, atomic_t *v)		\
 	smp_mb();							\
 									\
 	__asm__ __volatile__(						\
-	"1:				\n"				\
-	PREFETCHW							\
-	"	llock   %0, [%1]	\n"				\
+	"1:	llock   %0, [%1]	\n"				\
 	"	" #asm_op " %0, %0, %2	\n"				\
 	"	scond   %0, [%1]	\n"				\
 	"	bnz     1b		\n"				\