staging: vchi: Add SPDX-License-Identifier

Using multiple license representation as shown here [1].
[1] https://spdx.org/sites/cpstandard/files/pages/files/using_spdx_license_list_short_identifiers.pdf



Signed-off-by: André Almeida <andrealmeid@riseup.net>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>