Add GFX908 specific changes to HIP (#1229)

* Add GFX908 specific for HIP

* Fix missing __halfTest in hipTestNativeHalf

hipamd/tests/src/deviceLib/hipTestNativeHalf.cpp

@@ -32,7 +32,7 @@ THE SOFTWARE.
 
 using namespace std;
 
-#if __HIP_ARCH_GFX803__ || __HIP_ARCH_GFX900__ || __HIP_ARCH_GFX906__
+#if __HIP_ARCH_GFX803__ || __HIP_ARCH_GFX900__ || __HIP_ARCH_GFX906__ || __HIP_ARCH_GFX908__
 
 __global__
 void __halfTest(bool* result, __half a) {