ANDROID: KVM: arm64: allow nvhe/trace.h for in-tree/DDK pKVM modules

For both in-tree and DDK pKVM modules, it is now adviced to use
nvhe/trace.h instead of a simple trace.h. This is clearer.

Putting it in `nvhe/` also allows us to add pkvm_headers_aarch64 to
all_headers_allowlist_aarch64 directly, so that DDK pKVM modules don't
have to add pkvm_headers_aarch64 explicitly.

To keep backwards compatibility, this commit does not disallow using
`#include "trace.h"` directly. This will be removed in the follow up
CL.

To keep in-tree and DDK pKVM modules's -I flags in sync, add an IFTTT
block.

NO_IFTTT=This is the initial creation of the block.

Bug: 416603216
Bug: 357781595
Change-Id: Iac90750d4442539d12099eb09ba4cb2946956ef2
Signed-off-by: HONG Yifan <elsk@google.com>