treewide: remove references to CREDITS ...

The CREDITS file was removed from barebox in 2015 by commit 6570288f2d97
("Remove the CREDITS file"). Remove references to it from several files.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

include: add SPDX GPL-2.0-only license tags where applicable ...

Interpret "GPLv2" as "GPLv2 only".

Signed-off-by: Roland Hieber <rohieb@rohieb.name>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

login: cleanup password code ...

- make some locally used functions static
- remove read_passwd which is unused
- some refactoring to make code pathes clearer

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

login: rework login mechanism ...

We used to have the login functionality in the /env/bin/init script.
This is hard to review and it's too easy to break the login functionality
with changes to this script. Move the places to ask for a password to
C code where we have only a few places where we have to ask for a password.
Mainly these are run_shell() and the menutree command.

This patch introduces a login() function which will only return if the correct
password has been entered. Following calls will return immediately without
asking for a password again.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

login/passwd: add default password support ...

even if the env is broken you will have a password

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

Treewide: remove address of the Free Software Foundation ...

The FSF address has changed in the past. Instead of updating it
each time the address changes, just drop it completely treewide.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

login: add timeout support ...

If a timeout is specified and expired the command will be executed
by default boot

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

add password framework ...

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>