TF-A: Install armclang 6.8 toolchain

The armclang 6.8 toolchain is used by the following build configurations:

 * juno-default-armclang
 * fvp-default-armclang

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I92c6785164f3ba981bc0879f879076044d640a3c
1 file changed