eal: use same atomic intrinsics for GCC and clang

[ upstream commit 0c0eb1156e3d52ede4b19d687aa5387d1dca7666 ]

The size generic atomic intrinsics generate the same
code as the size specific intrinsics for gcc. Use size
generic intrinsics for both gcc and clang.

Fixes: 7bdccb9 ("eal: fix ARM build with clang")

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>

lib/librte_eal/include/generic/rte_atomic.h

@@ -175,11 +175,7 @@ rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val);
 static inline uint16_t
 rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val)
 {
-#if defined(__clang__)
 	return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
-#else
-	return __atomic_exchange_2(dst, val, __ATOMIC_SEQ_CST);
-#endif
 }
 #endif
 
@@ -458,11 +454,7 @@ rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val);
 static inline uint32_t
 rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val)
 {
-#if defined(__clang__)
 	return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
-#else
-	return __atomic_exchange_4(dst, val, __ATOMIC_SEQ_CST);
-#endif
 }
 #endif
 
@@ -740,11 +732,7 @@ rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val);
 static inline uint64_t
 rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val)
 {
-#if defined(__clang__)
 	return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
-#else
-	return __atomic_exchange_8(dst, val, __ATOMIC_SEQ_CST);
-#endif
 }
 #endif