Minor fix to unattended_install.cdrom.floppy_ks for legacy SLES

1) change dest_fname to "autounattend.xml", as most cfg used.
2) change autoyast_param from floppy to 'autoyast=device://fd0/autounattend.xml'
    for old SLES OS compatibility.
3) add kernel_params for all existing SLES

Signed-off-by: Xiaoqing Wei <xwei@redhat.com>