greybus: fw-management: Update header's license

The header should include both BSD and GPLv2 licenses and so should have
been a copy of greybus_protocols.h. This file had only the GPLv2 bits
earlier, update it to include BSD bits as well.

Reported-by: Greg Kroah-Hartman <gregkh@google.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>