hipHostRegister and hipHostMalloc refactor.

Note hipHostMalloc (not hipHostAlloc or hipMallocHost).
 -  the hipHost* is used for all HIP APIs dealing with Host memory.
    (including hipHostMalloc, hipHostFree, hipHostRegister,
hipHostUnregister, hipHostGetFlags, hipHostGetDevicePointer).
  - hipMallocHost is consistent with "hipMalloc" for allocating device
    memory.  Enumerations hipHostMalloc* also used as optional
    flags parm to hipHostMalloc.

hipamd/include/hip_runtime_api.h

@@ -220,8 +220,8 @@ static inline hipError_t hipMalloc ( T** devPtr, size_t size)
 
 // Provide an override to automatically typecast the pointer type from void**, and also provide a default for the flags.
 template<class T>
-static inline hipError_t hipHostAlloc( T** ptr, size_t size, unsigned int flags = hipHostAllocDefault)
+static inline hipError_t hipHostMalloc( T** ptr, size_t size, unsigned int flags = hipHostMallocDefault)
 {
-    return hipHostAlloc((void**)ptr, size, flags);
+    return hipHostMalloc((void**)ptr, size, flags);
 }
 #endif