ARM/omap1: switch to use dma_direct_set_offset for lbus DMA offsets

Switch the omap1510 platform ohci device to use dma_direct_set_offset
to set the DMA offset instead of using direct hooks into the DMA
mapping code and remove the now unused hooks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Acked-by: Tony Lindgren <tony@atomide.com>