CONFIG_AUTOBOOT_KEYED_CTRLC default yes?

[Zubair Lutfullah Kakakhel]

Hi,

I have a pi4 running u-boot 2019.01.
When I use the following config options

```
CONFIG_AUTOBOOT=y
# CONFIG_AUTOBOOT_KEYED is not set
```

CTRL-C would continue to interrupt autoboot.
Was quite surprised to see that.

Took a look at the code.
https://github.com/u-boot/u-boot/blob/master/common/autoboot.c#L367-L375

```
lock = IS_ENABLED(CONFIG_AUTOBOOT_KEYED) &&
!IS_ENABLED(CONFIG_AUTOBOOT_KEYED_CTRLC);
if (lock)
prev = disable_ctrlc(1); /* disable Ctrl-C checking */
```

So if `CONFIG_AUTOBOOT_KEYED=y` and `CONFIG_AUTOBOOT_KEYED_CTRLC=N`,
then disable ctrl-c checking.

That means if we disable `CONFIG_AUTOBOOT_KEYED`, we can still end up
with ctrl-c checking?

Why is Ctrl-C checking default ON instead of being enabled only when
`CONFIG_AUTOBOOT_KEYED_CTRLC=y`

Am I missing something here?

Thanks
ZubairLK