staging: nvec: send suspend messages synchronously

The suspend commands need to be sent using the
synchronous method, otherwise the power gets
disabled before the messages are transferred.

Signed-off-by: Marc Dietrich <marvin24@gmx.de>
[jak@jak-linux.org: Rewrote commit message]
Signed-off-by: Julian Andres Klode <jak@jak-linux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>