riscv: dts: thead: convert isa detection to new properties

Convert the th1520 devicetrees to use the new properties
"riscv,isa-base" & "riscv,isa-extensions".
For compatibility with other projects, "riscv,isa" remains.

Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
Acked-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231022154135.3746-1-jszhang@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/riscv/boot/dts/thead/th1520.dtsi

@@ -20,6 +20,9 @@
 			compatible = "thead,c910", "riscv";
 			device_type = "cpu";
 			riscv,isa = "rv64imafdc";
+			riscv,isa-base = "rv64i";
+			riscv,isa-extensions = "i", "m", "a", "f", "d", "c", "zicntr", "zicsr",
+					       "zifencei", "zihpm";
 			reg = <0>;
 			i-cache-block-size = <64>;
 			i-cache-size = <65536>;
@@ -41,6 +44,9 @@
 			compatible = "thead,c910", "riscv";
 			device_type = "cpu";
 			riscv,isa = "rv64imafdc";
+			riscv,isa-base = "rv64i";
+			riscv,isa-extensions = "i", "m", "a", "f", "d", "c", "zicntr", "zicsr",
+					       "zifencei", "zihpm";
 			reg = <1>;
 			i-cache-block-size = <64>;
 			i-cache-size = <65536>;
@@ -62,6 +68,9 @@
 			compatible = "thead,c910", "riscv";
 			device_type = "cpu";
 			riscv,isa = "rv64imafdc";
+			riscv,isa-base = "rv64i";
+			riscv,isa-extensions = "i", "m", "a", "f", "d", "c", "zicntr", "zicsr",
+					       "zifencei", "zihpm";
 			reg = <2>;
 			i-cache-block-size = <64>;
 			i-cache-size = <65536>;
@@ -83,6 +92,9 @@
 			compatible = "thead,c910", "riscv";
 			device_type = "cpu";
 			riscv,isa = "rv64imafdc";
+			riscv,isa-base = "rv64i";
+			riscv,isa-extensions = "i", "m", "a", "f", "d", "c", "zicntr", "zicsr",
+					       "zifencei", "zihpm";
 			reg = <3>;
 			i-cache-block-size = <64>;
 			i-cache-size = <65536>;