staging: greybus: remove license "boilerplate"

When the greybus drivers were converted to SPDX identifiers for the
license text, some license boilerplate was not removed.  Clean this up
by removing this unneeded text now.

Cc: Johan Hovold <johan@kernel.org>
Cc: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Cc: "Bryan O'Donoghue" <pure.logic@nexus-software.ie>
Cc: greybus-dev@lists.linaro.org
Cc: devel@driverdev.osuosl.org
Acked-by: Mark Greer <mgreer@animalcreekk.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Alex Elder <elder@kernel.org>
Link: https://lore.kernel.org/r/20190825055429.18547-3-gregkh@linuxfoundation.org


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