Remove duplicate key

Removes duplicate generate_disks_arm key

script/netbootxyz-overrides.yml

@@ -8,7 +8,6 @@ bootloader_disks:
   - "netboot.xyz"
   - "netboot.xyz-packet"
 generate_signatures: true
-generate_disks_arm: true
 sigs_dir: "{{ netbootxyz_root }}/sigs"
 sigs_location: "http://${boot_domain}/sigs/"
 cert_dir: "/ansible/certs"