staging/vme_user: fix usage of the slave resources after they've been freed

buf_unalloc() frees the memory buffers allocated with vme_alloc_consistent.
The associated VME resource is needed in both vme_alloc_consistent and
vme_free_consistent; however the slave VME resources are being freed before
the calls to vme_free_consistent are made, which means the buffers
are never returned.

Fix this by freeing the VME resources only after the consistent buffers have
been returned.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Acked-by: Martyn Welch <martyn.welch@ge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>