Memory-mapped dw_spi driver

Adds a memory-mapped I/O dw_spi platform device.

Signed-off-by: Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 28becdd..201746a 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -334,6 +334,10 @@
 	tristate "PCI interface driver for DW SPI core"
 	depends on SPI_DESIGNWARE && PCI
 
+config SPI_DW_MMIO
+	tristate "Memory-mapped io interface driver for DW SPI core"
+	depends on SPI_DESIGNWARE
+
 #
 # There are lots of SPI device types, with sensors and memory
 # being probably the most widely used ones.