use name and not device

src/lib/bootloader/device_map.rb

@@ -119,7 +119,7 @@ def order_boot_device
       # want to modify its MBR. So we get disk of such partition and change order to add it
       # to top of device map. For details see bnc#887808,bnc#880439
       boot_disk = Yast::BootStorage.disk_with_boot_partition
-      priority_disks = ::Bootloader::Stage1Device.new(boot_disk).real_devices
+      priority_disks = ::Bootloader::Stage1Device.new(boot_disk.name).real_devices
       # if none of priority disk is hd0, then choose one and assign it
       return if any_first_device?(priority_disks)