ioemu: generic PCI device config-space emulation

ioemu: generic PCI device config-space emulation

This patch is an extension for qemu-dm to enable emulation of generic
PCI devices. The information for the PCI devices can be passed by
command line parameter.

The command line parameter is "-pciemulation" followed by the
information which contains a label and hex value of the configuration
registers separated by ":".

The configuration registers for each PCI device are below.
vendorid
deviceid
command
status
revision
classcode
headertype
subvendorid
subsystemid
interruputline
interruptpin

This is an example of command line parameter.

 -pciemulation hba1:1240:0780:0002:0:0:010000:0:10b5:0777:05:1

Signed-off-by: Shinji Matsumoto <smatsumoto@marathontechnologies.com>