This is a first baby step towards removing widespread inclusion of
cpu.h and compiling more devices once (so that arm, aarch64 and
in the future target-multi can share the object files).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: changed __FUNCTION__ to __func__ since we're touching
 these lines of code anyway]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>