Merge branch 'dma_rmb_wmb'

Alexander Duyck says:

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Replace wmb()/rmb() with dma_wmb()/dma_rmb() where appropriate

This is a start of a side project cleaning up the drivers that can make use
of the dma_wmb and dma_rmb calls.  The general idea is to start removing
the unnecessary wmb/rmb calls from a number of drivers and to make use of
the lighter weight dma_wmb/dma_rmb calls as this should allow for an
overall improvement in performance as each barrier can cost a significant
number of cycles and on architectures such as x86 this is unnecessary.

These changes are what I would consider low hanging fruit.  The likelihood
of the changes introducing an error should be low since the use of the
barriers in these cases are fairly obvious.
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Signed-off-by: David S. Miller <davem@davemloft.net>