Add PCI interface support for PVPANIC device. Create a new file pvpanic-pci.c
where the PCI specific routines reside and update the build system with the new
files and config structure.

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>