serial: sh-sci: Add DMA support.

Support using DMA for sending and receiving data over SCI(F) interfaces of
various SH SoCs.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 888a0ce..11ebe86 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1009,6 +1009,10 @@
 	depends on SERIAL_SH_SCI=y
 	select SERIAL_CORE_CONSOLE
 
+config SERIAL_SH_SCI_DMA
+	bool "DMA support"
+	depends on SERIAL_SH_SCI && SH_DMAE && EXPERIMENTAL
+
 config SERIAL_PNX8XXX
 	bool "Enable PNX8XXX SoCs' UART Support"
 	depends on MIPS && (SOC_PNX8550 || SOC_PNX833X)