[ARM] pxa: remove now unnecessary dma_needs_bounce()

[ARM] pxa: remove now unnecessary dma_needs_bounce()

With a correct dev->dma_mask before calling dmabounce_register_dev(),
dma_needs_bounce() is not necessary.

The sa1111, though, is a bit complicated. Until it's fully understood
and fixed, dma_needs_bounce() for sa1111 is kept if CONFIG_SA1111 is
enabled with no side effect (with the condition of machine_is_*)

Thanks for Mike Rapoport to fix one error in the original version of
the patch and get this tested.

Acked-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>