ARM: dts: BCM53573: Relicense Luxul files to the GPL 2.0+ / MIT

This matches licensing used by other BCM53573 files and BCM5301X.

Signed-off-by: Dan Haab <dan.haab@luxul.com>
Acked-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>