nv.autoboot=abort has been added as development aid to have barebox stop
at the shell prompt automatically. It makes sense to inhibit all watchdogs
in this mode, so the user can later use the shell in peace.

This also applies to fastboot aborting the shell prompt. If this
happens, watchdog will be automatically inhibited as well.
Behavior on user aborting the shell prompt via keypad or uart input
remains unchanged for backwards-compatibility.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>