This is a temporary fix, but I can build it by adding the missing files and generating the files needed to build the module, as shown in the link.
The command I ran is below.
cd /usr/src/linux-headers-5.10.110-rockchip-rk3588
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/arch/arm64/kernel/vdso/vdso.lds.S -P arch/arm64/kernel/vdso
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/arch/arm64/kernel/vdso/vgettimeofday.c -P arch/arm64/kernel/vdso
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/lib/vdso/gettimeofday.c -P lib/vdso
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/arch/arm64/kernel/vdso/note.c -P arch/arm64/kernel/vdso
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/arch/arm64/kernel/vdso/note.S -P arch/arm64/kernel/vdso
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/arch/arm64/kernel/vdso/sigreturn.S -P arch/arm64/kernel/vdso
wget https://raw.githubusercontent.com/torvalds/linux/v5.10/arch/arm64/kernel/vdso/gen_vdso_offsets.sh -P arch/arm64/kernel/vdso
chmod +x arch/arm64/kernel/vdso/gen_vdso_offsets.sh
make KERNELVERSION=5.10.110-rockchip-rk3588 modules_prepare
https://github.com/armbian/build/issues/2734#issuecomment-950277542