Fix tps-rpmtest failing due /boot/grub2/grubenv attributes mismatch
    
    The /boot/grub2/grubenv file is not installed by the grub2 packages but
    is either a symbolic link created on %install or a regular file created
    by Anaconda during installation.
    
    This is causing the tps-rpmtest to fail in some architectures since the
    file attributes don't match what's expected by the package. Because is
    a special file, make verification  to ignore the size, mode, checksum
    and mtime attributes.
    
    Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>