vfio/pci: Intel IGD host and LCP bridge config space access

Provide read-only access to PCI config space of the PCI host bridge
and LPC bridge through device specific regions.  This may be used to
configure a VM with matching register contents to satisfy driver
requirements.  Providing this through the vfio file descriptor removes
an additional userspace requirement for access through pci-sysfs and
removes the CAP_SYS_ADMIN requirement that doesn't appear to apply to
the specific devices we're accessing.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index e622982..255a211 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -283,7 +283,10 @@
 #define VFIO_REGION_TYPE_PCI_VENDOR_TYPE	(1 << 31)
 #define VFIO_REGION_TYPE_PCI_VENDOR_MASK	(0xffff)
 
+/* 8086 Vendor sub-types */
 #define VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION	(1)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG	(2)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG	(3)
 
 /**
  * VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,