ARM: dts: r8a7791: Remove CMT renesas,channels-mask

Update the DTS to remove the now deprecated "renesas,channels-mask"
property.

The channel information is now kept in the device driver and can easily
be determined based on the compat string.
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7791.dtsi

@@ -266,8 +266,6 @@ cmt0: timer@ffca0000 {
 		power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
 		resets = <&cpg 124>;
 
-		renesas,channels-mask = <0x60>;
-
 		status = "disabled";
 	};
 
@@ -287,8 +285,6 @@ cmt1: timer@e6130000 {
 		power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
 		resets = <&cpg 329>;
 
-		renesas,channels-mask = <0xff>;
-
 		status = "disabled";
 	};