hw/arm/allwinner-a10: Do not use nd_table in instance_init function

hw/arm/allwinner-a10: Do not use nd_table in instance_init function

The instance_init function of a device can be called at any time, even
if the device is not going to be used (i.e. not going to be realized).
So a instance_init function must not do things that could cause QEMU
to exit, like calling qemu_check_nic_model(&nd_table[0], ...) for example.
But this is what the instance_init function of the allwinner-a10 device
is currently doing - and this causes QEMU to quit unexpectedly when
you run the 'device-list-properties' QMP command for example:

$ echo "{'execute':'qmp_capabilities'}"\
       "{'execute':'device-list-properties',"\
       " 'arguments':{'typename':'allwinner-a10'}}" \
       | arm-softmmu/qemu-system-arm -M mps2-an505,accel=qtest -qmp stdio
{"QMP": {"version": {"qemu": {"micro": 91, "minor": 11, "major": 2},
 "package": "build-all"}, "capabilities": []}}
{"return": {}}
Unsupported NIC model: lan9118

... and QEMU quits after printing the last line (which should not happen
just because of running 'device-list-properties' here).

And with the cubieboard, this even causes QEMU to abort():

$ echo "{'execute':'qmp_capabilities'}"\
       "{'execute':'device-list-properties',"\
       " 'arguments':{'typename':'allwinner-a10'}}" \
       | arm-softmmu/qemu-system-arm -M cubieboard,accel=qtest -qmp stdio
{"QMP": {"version": {"qemu": {"micro": 91, "minor": 11, "major": 2},
 "package": "build-all"}, "capabilities": []}}
{"return": {}}
Unexpected error in error_set_from_qdev_prop_error() at hw/core/qdev-properties.c:1095:
Property 'allwinner-emac.netdev' can't take value 'hub0port0', it's in use
Aborted (core dumped)

To fix the problem we've got to move the offending code to the realize
function instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-id: 1522862420-7484-1-git-send-email-thuth@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>