drivers/infiniband: Remove now-redundant smp_read_barrier_depends()

The smp_read_barrier_depends() does nothing at all except on DEC Alpha,
and no current DEC Alpha systems use Infiniband:

	lkml.kernel.org/r/20171023085921.jwbntptn6ictbnvj@tower

This commit therefore makes Infiniband depend on !ALPHA and removes
the now-ineffective invocations of smp_read_barrier_depends() from
the InfiniBand driver.

Please note that this patch should not be construed as my saying that
InfiniBand's memory ordering is correct, but rather that this patch does
not in any way affect InfiniBand's correctness.  In other words, the
result of applying this patch is bug-for-bug compatible with the original.

Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Doug Ledford <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Michael Cree <[email protected]>
Cc: Andrea Parri <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>
[ paulmck: Removed drivers/dma/ioat/dma.c per Jason Gunthorpe's feedback. ]
Acked-by: Jason Gunthorpe <[email protected]>

0 files changed, 0 insertions, 0 deletions