ARM: dts: imx7s: Do not claim i.MX51 compatibility for SRC

System Reset Controller in i.MX7 doesn't have any commonality with IP
block found in i.MX5 and i.MX6 SoC families. Given that and the new
upstream driver for i.MX7 variant (see
https://lkml.org/lkml/2017/2/21/466) remove "fsl,imx51-src" from
compatibility string.

Cc: [e-mail]
Cc: Fabio Estevam <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Andrey Smirnov <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm/boot/dts/imx7s.dtsi

···
 			};
 
 			src: src@30390000 {
-				compatible = "fsl,imx7d-src", "fsl,imx51-src", "syscon";
+				compatible = "fsl,imx7d-src", "syscon";
 				reg = <0x30390000 0x10000>;
 				interrupts = <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>;
 				#reset-cells = <1>;