Now that we properly set the physical address in the program header of the
vmlinux ELF we can extract it to properly set the load and entry point for
u-boot uImages.  Before we always hard coded the load & entry point to 0.
However there are situations that the kernel may be built with a non-zero
physical address.

We use objdump to extract the PHDR.  We assume that there is only one
PHDR in the vmlinux of type LOAD.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>