ARM: dts: keystone: Add ti,keystone-spi for SPI

Add ti,keystone-spi to the compatible field for the SPI node. This new
entry insures that the proper prescaler limit is used for keystone devices

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>

arch/arm/boot/dts/keystone.dtsi

@@ -136,7 +136,7 @@
 		};
 
 		spi0: spi@21000400 {
-			compatible = "ti,dm6441-spi";
+			compatible = "ti,keystone-spi", "ti,dm6441-spi";
 			reg = <0x21000400 0x200>;
 			num-cs = <4>;
 			ti,davinci-spi-intr-line = <0>;
@@ -147,7 +147,7 @@
 		};
 
 		spi1: spi@21000600 {
-			compatible = "ti,dm6441-spi";
+			compatible = "ti,keystone-spi", "ti,dm6441-spi";
 			reg = <0x21000600 0x200>;
 			num-cs = <4>;
 			ti,davinci-spi-intr-line = <0>;
@@ -158,7 +158,7 @@
 		};
 
 		spi2: spi@21000800 {
-			compatible = "ti,dm6441-spi";
+			compatible = "ti,keystone-spi", "ti,dm6441-spi";
 			reg = <0x21000800 0x200>;
 			num-cs = <4>;
 			ti,davinci-spi-intr-line = <0>;