Avoid grub2-efi package to overwrite existing /boot/grub2/grubenv file
    
    The grub2-efi package create a /boot/grub2/grubenv symlink that points to
    /boot/efi/EFI/fedora/grubenv that's where the real grubenv file is looked
    up by GRUB on an EFI installation.
    
    But currently if the grub2-efi is installed on a legacy BIOS install, it
    will overwrite an existing /boot/grub2/grubenv file with a broken symlink.
    
    So mark it as %config(noreplace) to avoid loosing an existing grubenv.
    
    Resolves: rhbz#1687323
    
    Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>