Rename teesmc_st.h to teesmc_optee.h

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (QEMU virt platform)
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
Travis: checkpatch: do not warn on file addition/removal

Signed-off-by: Pascal Brand <pascal.brand@st.com>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
build: print 'AS' instead of 'CC' when input file is assembly

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>