dm: exynos: Convert SPI to driver model

Move the exynos SPI driver over to driver model. This removes quite a bit
of boilerplate from the driver, although it adds some for driver model.

A few device tree additions are needed to make the SPI flash available.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>

arch/arm/dts/exynos5250-snow.dts

@@ -53,6 +53,14 @@
 		};
 	};
 
+	spi@12d30000 {
+		spi-max-frequency = <50000000>;
+		firmware_storage_spi: flash@0 {
+			compatible = "spi-flash";
+			reg = <0>;
+		};
+	};
+
 	spi@131b0000 {
 		spi-max-frequency = <1000000>;
 		spi-deactivate-delay = <100>;

arch/arm/dts/exynos5420-peach-pit.dts

@@ -140,6 +140,7 @@
 	spi@12d30000 { /* spi1 */
 		spi-max-frequency = <50000000>;
 		firmware_storage_spi: flash@0 {
+			compatible = "spi-flash";
 			reg = <0>;
 
 			/*