x86: put generic mm_hooks include into PARAVIRT

With PARAVIRT, we actually have arch_{dup,exit}_mmap functions,
so we can't include the generic header

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>