kernel: Force disable LLVM HIP

Gets rid of the following from clang -v:

```
Found HIP installation: /opt/rocm, version 5.4.22804
```

Change-Id: Ic58b3fb2dd67d345372bec7f5d2cf023ed2fb34d
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index 40285e5..80a895f 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -239,7 +239,7 @@
     endif
     PATH_OVERRIDE += PATH=$(TARGET_KERNEL_CLANG_PATH)/bin:$$PATH
     ifeq ($(KERNEL_CC),)
-        KERNEL_CC := CC="$(CCACHE_BIN) clang --cuda-path=/dev/null"
+        KERNEL_CC := CC="$(CCACHE_BIN) clang --cuda-path=/dev/null --hip-path=/dev/null"
     endif
 endif