KVM: PPC: e500: merge <asm/kvm_e500.h> into arch/powerpc/kvm/e500.h

Keeping two separate headers for e500-specific things was a
pain, and wasn't even organized along any logical boundary.

There was TLB stuff in <asm/kvm_e500.h> despite the existence of
arch/powerpc/kvm/e500_tlb.h, and nothing in <asm/kvm_e500.h> needed
to be referenced from outside arch/powerpc/kvm.

Signed-off-by: Scott Wood <scottwood@freescale.com>
[agraf: fix bisectability]
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>