Align trace levels to the ones of optee_os

Signed-off-by: Pascal Brand <pascal.brand@st.com>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Fixes on trace levels

Signed-off-by: Pascal Brand <pascal.brand@st.com>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Pascal Brand <pascal.brand@linaro.org> (STM platform)
Travis: use default arm-linux-gnueabihf- compiler

The download of the Linaro compiler as well as the installation of
its dependencies (including some 32-bit libraries) is replaced by
the installation of the default gcc-arm-linux-gnueabihf package.

This speeds up the build significantly.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>