hw/arm/sysbus-fdt: Only call match_fn callback if the type matches

hw/arm/sysbus-fdt: Only call match_fn callback if the type matches

Commit af7d64ede0b9 (hw/arm/sysbus-fdt: Allow device matching with DT
compatible value) introduced a match_fn callback which gets called
for each registered combo to check whether a sysbus device can be
dynamically instantiated. However the callback gets called even if
the device type does not match the binding combo typename field.
This causes an assert when passing "-device ramfb" to the qemu
command line as vfio_platform_match() gets called on a non
vfio-platform device.

To fix this regression, let's change the add_fdt_node() logic so
that we first check the type and if the match_fn callback is defined,
then we also call it.

Binding combos only requesting a type check do not define the
match_fn callback.

Fixes: af7d64ede0b9 (hw/arm/sysbus-fdt: Allow device matching with
DT compatible value)

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reported-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Message-id: 20181106184212.29377-1-eric.auger@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>