arm: sunxi: Allwinner A10 SPI driver

Add spi driver for sun4i, sun5i and sun7i SoCs. The driver is
adapted from mailine kernel.

Signed-off-by: Stefan Mavrodiev <stefan@olimex.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index b85fca5..dcd719f 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -174,6 +174,11 @@
 	  used to access the SPI NOR flash chips on platforms embedding
 	  this ST IP core.
 
+config SUN4I_SPI
+	bool "Allwinner A10 SoCs SPI controller"
+	help
+	  SPI driver for Allwinner sun4i, sun5i and sun7i SoCs
+
 config TEGRA114_SPI
 	bool "nVidia Tegra114 SPI driver"
 	help