If NO_DMA=y:

    ERROR: "dma_unmap_sg" [drivers/tty/serial/mxs-auart.ko] undefined!
    ERROR: "dma_map_sg" [drivers/tty/serial/mxs-auart.ko] undefined!

Add a dependency on HAS_DMA to fix this.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>