KVM: PPC: Book3S HV P9: Reflect userspace hcalls to hash guests to support PR KVM

The reflection of sc 1 interrupts from guest PR=1 to the guest kernel is
required to support a hash guest running PR KVM where its guest is
making hcalls with sc 1.

In preparation for hash guest support, add this hcall reflection to the
P9 path. The P7/8 path does this in its realmode hcall handler
(sc_1_fast_return).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-30-npiggin@gmail.com