use FirstSetBit_Hi() instead as firstbithigh()

use FirstSetBit_Hi() instead as firstbithigh()

Assets/ScriptableRenderLoop/common/ShaderBase.h

 #endif
 
 #ifndef firstbithigh
-	#define firstbithigh		FirstSetBit_Hi_MSB
+	#define firstbithigh		FirstSetBit_Hi
 #endif
 
 #endif