Add initrd line for slackware

roles/netbootxyz/templates/menu/slackware.ipxe.j2

@@ -26,6 +26,6 @@ goto boot
 imgfree
 kernel ${slackware_mirror}/${dir}/kernels/huge.s/bzImage
 initrd ${slackware_mirror}/${dir}/isolinux/initrd.img
-imgargs bzImage load_ramdisk=1 prompt_ramdisk=0 rw printk.time=0 SLACK_KERNEL=huge.s ${params} ${cmdline}
+imgargs bzImage load_ramdisk=1 prompt_ramdisk=0 rw printk.time=0 tz=localtime initrd=initrd.magic ${cmdline}
 isset ${debug} && prompt ||
 boot