nextthing/chip: don't import image.nix by default

Fix the CI error:

	error: The option `fileSystems."/".fsType' has conflicting definition values:
	- In `/nix/store/...-source/pkgs/top-level/all-packages.nix': "btrfs"
	- In `/nix/store/...-source/nixos/modules/installer/sd-card/sd-image.nix': "ext4"

Author: chuangzhu

nextthing/chip/README.md

@@ -13,6 +13,8 @@
         # If you are using PocketCHIP
         nixos-hardware.nixosModules.nextthing-chip-pocketchip
 
+        "${nixos-hardware}/nextthing/chip/image.nix"
+
         {
           # Cross compilation build architecture
           nixpkgs.buildPlatform.system = "x86_64-linux";

nextthing/chip/default.nix

@@ -2,7 +2,6 @@
   imports = [
     ./common.nix
     ./bluetooth.nix
-    ./image.nix
     ./nand.nix
   ];
 }