tools/memory-model: Clarify the origin/scope of the tool name

tools/memory-model: Clarify the origin/scope of the tool name

Ingo pointed out that:

  "The "memory model" name is overly generic, ambiguous and somewhat
   misleading, as we usually mean the virtual memory layout/model
   when we say "memory model". GCC too uses it in that sense [...]"

Make it clear that tools/memory-model/ uses the term "memory model" as
shorthand for "memory consistency model" by calling out this convention
in tools/memory-model/README.

Stick to the original "memory model" term in sources' headers and for
the subsystem name.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akiyks@gmail.com
Cc: boqun.feng@gmail.com
Cc: dhowells@redhat.com
Cc: j.alglave@ucl.ac.uk
Cc: linux-arch@vger.kernel.org
Cc: luc.maranget@inria.fr
Cc: nborisov@suse.com
Cc: npiggin@gmail.com
Link: http://lkml.kernel.org/r/1519169112-20593-1-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>