vfio: platform: add dev_info on device reset

It might be helpful for the end-user to check the device reset
function was found by the vfio platform reset framework.

Lets store a pointer to the struct device in vfio_platform_device
and trace when the reset function is called or not found.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>