staging: greybus: fix block comment

This patch fix the coding style problem of block comment detected by the
checkpatch.pl.

WARNING: Block comments use a trailing */ on a separate line

Signed-off-by: Hisao Tanabe <xtanabe@gmail.com>
Acked-by: Johan Hovold <johan@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>