IVGCVSW-1806 More Android NN Driver refactoring

 * Changed #if defined to #ifdef
 * Simplified the Android ML namespace resolution
 * Fixed the relative path in some include directives

Change-Id: I46e46faff98559c8042c1a4b8b82007f462df57d
diff --git a/ArmnnPreparedModel.cpp b/ArmnnPreparedModel.cpp
index 85251ef..d7f727f 100644
--- a/ArmnnPreparedModel.cpp
+++ b/ArmnnPreparedModel.cpp
@@ -301,7 +301,7 @@
 
 template class ArmnnPreparedModel<hal_1_0::HalPolicy>;
 
-#if defined(ARMNN_ANDROID_NN_V1_1)
+#ifdef ARMNN_ANDROID_NN_V1_1
 template class ArmnnPreparedModel<hal_1_1::HalPolicy>;
 #endif