AndroidKernel: Add LLVM support for Kernel

Add necessary changes to be able to compile the Kernel
with LLVM.
Also update for KERNEL_VM_* specific rules.

Change-Id: I147a7abc29ec66828e9626a74125d391f8aaa329
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
Signed-off-by: Shadab Naseem <snaseem@codeaurora.org>