plat: sim: extern put/getchar in case of conflict
Revert "plat: stm32: use full ram size for dfu mode"

This reverts commit 30b15fbf2f007ccec016c1131a778dbabf89d2c2.

If apply full 20K to application firmware, it may fail after
reset cause there will be corruption in bootloader used ram area.
console: cmd: add ? for help
core: add low level debug routine
plat: fixes for previous commit, func def missing
doc: update release notes for 0.2.1