buildroot

dtc: update legal info

library libdtc is dual licensed under BSD-2c or GPLv2+ and dtc programs
are licensed under GPLv2+.

This patch annotates licenses with components and uses correct format to
specify dual licensing that is separating licenses with 'or' keyword
instead of '/'.

Signed-off-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>