Add standalone host PBKDF2-HMAC-SHA256 mkpasswd, board_romfs_mkpasswd.sh,
and promptpasswd.sh with confirm-password support. Integrate ROMFS passwd
generation in Board.mk and CMake. Drop TEA key checks from passwd_keys.mk.
Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>