atomics/treewide: Clean up '*_andnot()' ifdeffery

The ifdeffery for atomic*_{fetch_,}andnot() is unlike that for all the
other atomics. If atomic*_andnot() is not defined, the corresponding
atomic*_fetch_andnot() is assumed to not be defined.

Additionally, the fallbacks for the various ordering cases are written
much later in atomic.h as static inlines.

This isn't problematic today, but gets in the way of scripting the
generation of atomics. To prepare for scripting, this patch:

* Switches to separate ifdefs for atomic*_andnot() and
  atomic*_fetch_andnot(), updating implementations as appropriate.

* Moves the fallbacks into the standards ifdefs, as macro expansions
  rather than static inlines.

* Removes trivial andnot implementations from architectures, where these
  are superseded by core code.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-19-mark.rutland@arm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>