ppc/pnv: Put "*-pnv-chip" and "pnv-xive" on the main system bus

ppc/pnv: Put "*-pnv-chip" and "pnv-xive" on the main system bus

pnv_init() creates "power10_v1.0-pnv-chip", "power8_v2.0-pnv-chip",
"power8e_v2.1-pnv-chip", "power8nvl_v1.0-pnv-chip", or
"power9_v2.0-pnv-chip" sysbus devices in a way that leaves them
unplugged.

pnv_chip_power9_instance_init() creates a "pnv-xive" sysbus device in
a way that leaves it unplugged.

Create them the common way that puts them into the main system bus.
Affects machines powernv8, powernv9, and powernv10.  Visible in "info
qtree".  Here's the change for powernv9:

     bus: main-system-bus
       type System
    +  dev: power9_v2.0-pnv-chip, id ""
    +    chip-id = 0 (0x0)
    +    ram-start = 0 (0x0)
    +    ram-size = 1879048192 (0x70000000)
    +    nr-cores = 1 (0x1)
    +    cores-mask = 72057594037927935 (0xffffffffffffff)
    +    nr-threads = 1 (0x1)
    +    num-phbs = 6 (0x6)
    +    mmio 000603fc00000000/0000000400000000
    [...]
    +  dev: pnv-xive, id ""
    +    ic-bar = 1692157036462080 (0x6030203100000)
    +    vc-bar = 1689949371891712 (0x6010000000000)
    +    pc-bar = 1690499127705600 (0x6018000000000)
    +    tm-bar = 1692157036986368 (0x6030203180000)

Cc: "Cédric Le Goater" <clg@kaod.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-ppc@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20200609122339.937862-17-armbru@redhat.com>