Migrate passwd encrypt/verify to PBKDF2 modular crypt format using
kernel cryptodev (CRYPTO_PBKDF2_HMAC_SHA256 via /dev/crypto). Add
passwd_pbkdf2 wrapper, base64url helpers, complexity validation, and
pbkdf2_test for RFC 6070 vector coverage. FSUTILS_PASSWD selects
CRYPTO, ALLOW_BSD_COMPONENTS, and CRYPTO_CRYPTODEV so existing sim
defconfigs keep building. Change NSH_LOGIN_USERNAME default to root and
remove fixed-login password defaults.
BREAKING CHANGE: TEA-encoded /etc/passwd entries no longer verify.
Regenerate each entry after upgrading. Pair with the nuttx host mkpasswd
changes in apache/nuttx#19209. Boards must enable the appropriate
software or hardware crypto backend for PBKDF2 at runtime. When
CONFIG_NSH_LOGIN_FIXED=y, set CONFIG_NSH_LOGIN_PASSWORD in the board
defconfig or menuconfig; there is no default password.
Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>
