The Kbuild system first looks for a Kbuild file, then it looks for
a make file.
Use the Kbuild for object building and leave the Makefile for definding
build options and compiler flags and other SoC related defines.
Change-Id: I0be59bb5ae02a29108a188efbd6f14dcdb7de4ee
Signed-off-by: Anas Nashif <anas.nashif@intel.com>