Cleanup files from code review.

- Remove some stale code
- Update docs
- Correct define for __HIP_ARCH_HAS_GLOBAL_INT64_ATOMICS__

Change-Id: Ic5e3cdb8269b1c18f6d2693700b55e08c4d0080e

include/hip/hcc_detail/hip_hcc.h

@@ -29,8 +29,6 @@ THE SOFTWARE.
 #error("This version of HIP requires a newer version of HCC.");
 #endif
 
-#define USE_MEMCPYTOSYMBOL
-
 #define USE_DISPATCH_HSA_KERNEL 0
 //
 

include/hip/nvcc_detail/hip_runtime.h

@@ -45,7 +45,7 @@ kernelName<<<numblocks,numthreads,memperblock,streamId>>>(0, ##__VA_ARGS__);\
 #define __HIP_ARCH_HAS_GLOBAL_FLOAT_ATOMIC_EXCH__   (__CUDA_ARCH__ >= 110)
 #define __HIP_ARCH_HAS_SHARED_INT32_ATOMICS__       (__CUDA_ARCH__ >= 120)
 #define __HIP_ARCH_HAS_SHARED_FLOAT_ATOMIC_EXCH__   (__CUDA_ARCH__ >= 120)
-#define __HIP_ARCH_HAS_FLOAT_ATOMIC_ADD__
+#define __HIP_ARCH_HAS_FLOAT_ATOMIC_ADD__           (__CUDA_ARCH__ >= 200)
 
 // 64-bit Atomics:
 #define __HIP_ARCH_HAS_GLOBAL_INT64_ATOMICS__       (__CUDA_ARCH__ >= 200)