x86: unify paravirt pieces of processor.h

This patch unifies the paravirt pieces of processor.h
The functionality present in 32 bit, but not (yet) in 64-bit,
like load_sp0 is _not_ done here, and let to a different patch.

With this unification, we get paravirt for free in x86_64 processor.h

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>