riscv: dts: allwinner: d1: fix vlenb property

According to [1], the C906 vector registers are 128 bits wide.
The 'thead,vlenb' property specifies the vector register length
in bytes, so its value must be set to 16.

[1] https://dl.linux-sunxi.org/D1/Xuantie_C906_R1S0_User_Manual.pdf

Fixes: ce1daee ("riscv: dts: allwinner: Add xtheadvector to the D1/D1s devicetree")
Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
Link: https://patch.msgid.link/20251119203508.1032716-1-geomatsi@gmail.com
Signed-off-by: Chen-Yu Tsai <wens@kernel.org>

Author: geomatsi

arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi

@@ -28,7 +28,7 @@
 			riscv,isa-base = "rv64i";
 			riscv,isa-extensions = "i", "m", "a", "f", "d", "c", "zicntr", "zicsr",
 					       "zifencei", "zihpm", "xtheadvector";
-			thead,vlenb = <128>;
+			thead,vlenb = <16>;
 			#cooling-cells = <2>;
 
 			cpu0_intc: interrupt-controller {