Use upstream xmake

Previously we use our own xmake because upstream one is broken, but it
was fixed upstream already.

Author: nbdd0121

flake.nix

@@ -90,8 +90,9 @@
         cheriot = pkgs.mkShell {
           name = "cheriot";
           packages =
-            (with lowrisc_pkgs; [llvm_cheriot xmake])
+            (with lowrisc_pkgs; [llvm_cheriot])
             ++ (with pkgs; [
+              xmake
               gnumake
               magic-enum
               srecord

pkgs/default.nix

@@ -19,7 +19,6 @@
   # CherIoT packages
   spike-ibex-cosim = pkgs.callPackage ./spike.nix {};
   llvm_cheriot = pkgs.callPackage ./llvm_cheriot.nix {};
-  xmake = pkgs.callPackage ./xmake {};
   cheriot-sim = pkgs.callPackage ./cheriot-sim.nix {};
   cheriot-audit = pkgs.callPackage ./cheriot-audit.nix {};