Merge pull request #184 from jcastillo-arm/jc/tf-issues/100

FVP: make usage of Trusted DRAM optional at build time

diff --cc docs/firmware-design.md
Simple merge

diff --cc docs/user-guide.md
Simple merge

diff --cc plat/fvp/bl1_fvp_setup.c
Simple merge

diff --cc plat/fvp/include/platform_def.h
Simple merge