buildroot

linux-fusion: bump to 9.0.3, use .tar.xz

This commit bumps linux-fusion to the latest upstream version, and
switches to use the more space efficient xz-compressed tarball.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>