[PATCH] mm: fill arch atomic64 gaps

alpha, sparc64, x86_64 are each missing some primitives from their atomic64
support: fill in the gaps I've noticed by extrapolating asm, follow the
groupings in each file.  But powerpc and parisc still lack atomic64.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@muc.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>