MAINTAINERS: Restore "L: linux-kernel@vger.kernel.org" entries

MAINTAINERS: Restore "L: linux-kernel@vger." entries

A couple of years ago all the "L: lkml" email list entries in
MAINTAINERS were removed and replaced with a 'the rest' entry
at the end of the file - under the theory that this is unnecessary
duplication and that people would find it intuitive:

  b5472cddbe2c MAINTAINERS: remove L: linux-kernel@vger.kernel.org from all but "THE REST"

So it turns out that it's all but intuitive, not all people
use scripts/get_maintainer.pl to extract maintainer contact info,
some people read the MAINTAINERS file and see the lack of 'L:' entries
of various lkml-only subsystems and are sending patches to the
maintainers only, without Cc:-ing lkml.  They arguably have a point.

In hindsight removing all the "L: lkml" entries was probably not
an overly good idea, not all mechanic duplication should be eliminated:
in files read by humans it's useful to have 'at a glance' summary for
all email addresses important to a subsystem's maintenance, in a single
place, without too many imported rules and assumptions.

So, to make the lkml fallback really apparent, add back 'L: lkml'
entries to all subsystem entries whose workflow I'm involved in.
This should at minimum be a per subsystem policy thing.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Joe Perches <joe@perches.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/n/tip-lhzlymtgmmv5bMuwsb5zyoYo@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>