If NO_DMA=y:

    ERROR: "bad_dma_ops" [drivers/ata/libata.ko] undefined!

To fix this, protect the DMA code by #ifdef CONFIG_HAS_DMA, and provide
dummies of ata_sg_clean() and ata_sg_setup() for the !CONFIG_HAS_DMA
case.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NTejun Heo <tj@kernel.org>