drm/radeon: Log Subsystem Vendor and Device Information

    Log PCI subsystem vendor and subsystem device ID in addition to
    PCI vendor and device ID during kernel mode initialisation. This helps
    to better identify radeon devices of third-party vendors, e. g. for
    bug analysis.

    Tested for kernel 2.6.35, 2.6.38 and 3.0 on Asus M2A-VM HDMI board

Cc: <stable@kernel.org>
Signed-off-by: Thomas Reim <reimth@gmail.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Acked-by: Stephen Michaels <Stephen.Micheals@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>