DMA-API: ata: pata_octeon_cf: convert to use dma_coerce_mask_and_coherent()

Convert this code sequence:
	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(64);
	pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
to use dma_coerce_mask_and_coherent() to avoid bypassing the architecture
check on the DMA mask.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>