I/O and debug function confusion

[mchack-work]

The debug functions putchar(), puts() et cetera currently only work on the QEMU debug port we added. This is confusing.

I suggest we change the names of these function to debug_*() or qemu_*() or something and also include real puts() et cetera that uses the UART.

[secworks]

I suggest using qemu_*() for functions only used in, makes sense in the QEMU model. It would make it very explicit and hard to misunderstand. I hope.

[quite]

This is similar in the fw for those functions that output to "htif console".

[mchack-work]

Merged in main repo and -apps.