KVM: PPC: Add QPR registers

The Gekko has GPRs, SPRs and FPRs like normal PowerPC codes, but
it also has QPRs which are basically single precision only FPU registers
that get used when in paired single mode.

The following patches depend on them being around, so let's add the
definitions early.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>