serial: SERIAL_IMX_AUART should depend on HAS_DMA

If NO_DMA=y:

    ERROR: "dma_unmap_sg" [drivers/tty/serial/imx.ko] undefined!
    ERROR: "dma_map_sg" [drivers/tty/serial/imx.ko] undefined!

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

drivers/tty/serial/Kconfig

@@ -572,6 +572,7 @@ config BFIN_UART3_CTSRTS
 
 config SERIAL_IMX
 	tristate "IMX serial port support"
+	depends on HAS_DMA
 	depends on ARCH_MXC || COMPILE_TEST
 	select SERIAL_CORE
 	select RATIONAL