kvm/powerpc: move kvm_hypercall0() and friends to epapr_hypercall0()

kvm_hypercall0() and friends have nothing KVM specific so moved to
epapr_hypercall0() and friends. Also they are moved from
arch/powerpc/include/asm/kvm_para.h to arch/powerpc/include/asm/epapr_hcalls.h

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>