vfio/display: Fix vfio_display_edid_init() error path

vfio/display: Fix vfio_display_edid_init() error path

vfio_display_edid_init() can fail for many reasons and return silently.
It would be good to report the error.

Old mdev driver may not support vfio edid region and we allow to go
through in this case.

vfio_display_edid_update() isn't changed because it can be called at
runtime when UI changes (i.e. window resize).

Fixes: 08479114b0de ("vfio/display: add edid support.")
Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>