vdpa: Fix an error handling path in eni_vdpa_probe()

After a successful vp_legacy_probe() call, vp_legacy_remove() should be
called in the error handling path, as already done in the remove function.

Add the missing call.

Fixes: e85087be ("eni_vdpa: add vDPA driver for Alibaba ENI")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Message-Id: <a7b0ef1eabd081f1c7c894e9b11de01678e85dee.1666293559.git.christophe.jaillet@wanadoo.fr>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>