ssb: return correct translation bit for 64-bit DMA

Remove b43's workarounds at the same time. Other users of
ssb_dma_translation do not support any 64-bit DMA devices, so they are
not affected.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>