MAINTAINERS: Add printk maintainers

MAINTAINERS: Add printk maintainers

I and Sergey would like to volunteer as printk code maintainers.
It is a code that everyone is using, various people fix bugs or
even add features but there is nobody really interested into
maintaining it.

I and Sergey have put a lot of effort into understanding the code
and related problems. We are working on solutions for some long
term problems. There is a nice summary from the Kernel Summit
presentation, see https://lwn.net/Articles/705938/

We have already started to use the gained knowledge and comment
on other printk-related patches. The official role should help
us to do it more effectively.

Our priorities are:

    + prevent deadlocks (printk_safe patchset, console locks)
    + prevent softlocks (async printk, console_sem and flushing)
    + handle other bugs/fixes/features as they come

with this in mind:

    + printk is used in different context
    + need special care in some modes, e.g. oops, panic, suspend
    + do best effort to store/show messages
    + the code is already pretty complicated and twisted;
      support clean ups; always think hard if a feature/fix
      is worth any complication

Of course, it still will be much appreciated if other people review
printk patches.

Regarding the workflow. It will be highly appreciated if the patches
might still go via Andrew's -mm tree at least for 4.10. In the long
term, we would like to make Andrew's life easier and handle printk
patches in an own git tree. But we first need to set it up and get
familiar with the processes.

Link: http://lkml.kernel.org/r/1481798878-31898-1-git-send-email-pmladek@suse.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>