x86: demacro pgalloc paravirt stubs

Turn paravirt stubs into inline functions, so that the arguments are
still typechecked.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>