Update 08-porting-to-hip.md

Author: csccva

docs/08-porting-to-hip.md

@@ -169,14 +169,14 @@ Hipify tools are not running your application, or checking correctness. Code rel
 **CUDA** ⇒ **HIP**
 ```
 export HOP_ROOT=/path/to/hop
-export HOP_FLAGS=-I$HOP_ROOT -I$HOP_ROOT/source/cuda -DHOP_TARGET_HIP
+export HOP_FLAGS="-I$HOP_ROOT -I$HOP_ROOT/source/cuda -DHOP_TARGET_HIP"
 CC -x hip $HOP_FLAGS hello.cu -o hello
 ./hello
 ```
 **HIP**  ⇒ **CUDA**
 ```
 export HOP_ROOT=/path/to/hop
-export HOP_FLAGS=-I$HOP_ROOT -I$HOP_ROOT/source/hip -DHOP_TARGET_CUDA
+export HOP_FLAGS="-I$HOP_ROOT -I$HOP_ROOT/source/hip -DHOP_TARGET_CUDA"
 CC -x cu $HOP_FLAGS hello.cpp -o hello
 ./hello
 ```