ppc/pnv: Add support for POWER8+ LPC Controller

It adds the Naples chip which supports proper LPC interrupts via the
LPC controller rather than via an external CPLD.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[clg: - updated for qemu-2.9
      - ported on latest PowerNV patchset
      - moved the IRQ handler in pnv_lpc.c
      - introduced pnv_lpc_isa_irq_create() to create the ISA IRQs ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>