rkboot: switch to qemu-x86_64

pkgs/by-name/rk/rkboot/package.nix

@@ -1,7 +1,7 @@
 { stdenv
 , lib
 , rkbin
-, box64
+, qemu
 }:
 
 stdenv.mkDerivation {
@@ -19,7 +19,7 @@ stdenv.mkDerivation {
     do
       # The proprietary, statically linked binaries to perform boot_merge are
       # x86_64 only. Though we use box64 to emulate if building on aarch64-linux
-      ${lib.optionalString stdenv.isAarch64 "${lib.getExe box64}"} ./tools/boot_merger "$i" || true
+      ${lib.optionalString stdenv.isAarch64 "${qemu}/bin/qemu-x86_64"} ./tools/boot_merger "$i" || true
     done
   '';