Makefile: place defaults values and macro defs in a separate folder

Although there are not many variable default values and macros
definitions, for modularity and scalability, place these two into a
separate folder.

Change-Id: If916a69edda07aaeaa77d60ce482e002effd7f9f
Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
3 files changed