vmci: type promotion bug in qp_host_get_user_memory()

The problem is that if get_user_pages_fast() fails and returns a
negative error code, it gets type promoted to a high positive value and
treated as a success.

Fixes: 06164d2b ("VMCI: queue pairs implementation.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>