remoteproc: fix error path of handle_vdev

Remove the vdev entry from the list before freeing it,
otherwise rproc->vdevs will explode.

Cc: stable@vger.kernel.org
Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Acked-by: Ido Yariv <ido@wizery.com>
[edit subject, minor commit log edit, cc stable]
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>