KVM: PPC: PR: Fill pvinfo hcall instructions in big endian

We expose a blob of hypercall instructions to user space that it gives to
the guest via device tree again. That blob should contain a stream of
instructions necessary to do a hypercall in big endian, as it just gets
passed into the guest and old guests use them straight away.

Signed-off-by: Alexander Graf <agraf@suse.de>