Copy common files from TF-A repository

From repo https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git
at SHA 91ff490d7 the following files have been taken:

 - common/tf_log.c
 - include/common/debug.h
 - include/lib/libc/cdefs.h
 - plat/arm/board/fvp/include/platform_def.h

Change-Id: If1336c02b44ddaa0c879ca2ca56b8414af6d8bf9
4 files changed