pseries: Implement hcall-bulk hypervisor interface

pseries: Implement hcall-bulk hypervisor interface

This patch adds support for the H_REMOVE_BULK hypercall on the pseries
machine.  Strictly speaking this isn't necessarym since the kernel will
only attempt to use this if hcall-bulk is advertised in the device tree,
which previously it was not.

Adding this support may give a marginal performance increase, but more
importantly it reduces the differences between the emulated machine and
an existing PowerVM or kvm system, both of which already implement
hcall-bulk.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>