staging: greybus: fix up SPDX comment in .h files

When these files originally got an SPDX tag, I used // instead of /* */
for the .h files.  Fix this up to use // properly.

Cc: Johan Hovold <johan@kernel.org>
Cc: greybus-dev@lists.linaro.org
Cc: devel@driverdev.osuosl.org
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Alex Elder <elder@kernel.org>
Link: https://lore.kernel.org/r/20190825055429.18547-2-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>