Revert "KVM: PPC: Add support for explicit HIOR setting"

This reverts commit a15bd354.

It exceeded the padding on the SREGS struct, rendering the ABI
backwards-incompatible.

Conflicts:

	arch/powerpc/kvm/powerpc.c
	include/linux/kvm.h

Signed-off-by: Avi Kivity <avi@redhat.com>