[POWERPC] bootwrapper: Preserve the pp pointer in ft_make_space() when calling ft_reorder().

The ft_reorder() function may change the start of the region of interest,
so the pointer provided by the caller into that region must be fixed up
to still point to the same datum.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>