kernel/linux: longterm kernel location changed

The location of the longterm Linux kernels on FTP has changed.
Here is a simple (but not very versatile) fix.

Signed-off-by: "Björn A. Herwig" <herwig@gdsys.de>
[yann.morin.1998@anciens.enib.fr: make it generic/versatile]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 reporter_name="Remy Bohmer"

 reporter_url="linux@bohmer.net"

 reporter_comment="Example for building a toolchain for m68000 bare metal targets"