package/rpi-firmware: bump marking script version

Changes since last version:
 - add support for lz4-compressed kernels,
 - add copyright and license banners,
 - enable warnings and fix a few uses of undefined variables,
 - update from the rpi-4.0.y kernel.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>