this will allow to generate a KEY + IV based on a password and salt for AES
encryption/decryption as example

or simply the key for hmac or rsa from text password

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>