Add links for toolchains not available on kernel.org.
The sh4 toolchains from kernel.org dose not work for some boards,
so use the sh from Sourcery.
Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>