ATHEROS-ALX: Use dma_set_mask_and_coherent and fix a bug

ATHEROS-ALX: Use dma_set_mask_and_coherent and fix a bug

1. For the 64 bits dma mask use dma_set_mask_and_coherent instead of
   dma_set_mask and dma_set_coherent_mask.

2. For the 32 bits dma mask dma_set_coherent_mask is only called if
   dma_set_mask fails, which is unusual. Assuming this as a bug, fixes
   it by replacing calls to dma_set_mask and dma_set_coherent_mask by a
   call to dma_set_mask_and_coherent.

Signed-off-by: Peter Senna Tschudin <[email protected]>
Tested-by: Jonas Hahnfeld <[email protected]>
Signed-off-by: David S. Miller <[email protected]>