Add the possibility to compile TF-A with more warnings
Add the possibility to compile TF-A with more warnings

The list of warning is taken from kernel and also divided in 3.
The option to activate that is W=x, with x=1, 2 or 3.

Signed-off-by: Yann Gautier <e753f6969c288905606e3c07464886d4f1fc1be0@st.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware