powerpc/bootwrapper: add fixed-head.o to simpleimage wrappers

fixed-head.o must be linked into the bootwrapper for raw-binary images to
work.  This patch adds it into the bootwrapper.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reported-by: Eddie Dawydiuk <eddie@embeddedarm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/boot/wrapper

@@ -214,11 +214,11 @@ simpleboot-virtex405-*)
     binary=y
     ;;
 simpleboot-virtex440-*)
-    platformo="$object/simpleboot.o $object/virtex.o"
+    platformo="$object/fixed-head.o $object/simpleboot.o $object/virtex.o"
     binary=y
     ;;
 simpleboot-*)
-    platformo="$object/simpleboot.o"
+    platformo="$object/fixed-head.o $object/simpleboot.o"
     binary=y
     ;;
 asp834x-redboot)