efi_loader: set image_base and image_size to correct values

Currently, image's image_base points to an address where the image was
temporarily uploaded for further loading. Since efi_loader relocates
the image to final destination, image_base and image_size should reflect
that.

This bug was detected in UEFI SCT, "Loaded Image Protocol Test - test 2,"
which shows that 'Unload' function doesn't fit into a range suggested by
image_base and image_size.

	TestCase/UEFI/EFI/Protocol/LoadedImage/BlackBoxTest/
	LoadedImageBBTestMain.c:1002

Changes in this patch also includes:
* reverts a patch, "efi_loader: save image relocation address
  and size" since newly added fields are no longer needed.
* copy PE headers as well since those information will be needed
  for module loading, in particular, at gurb.
  (This bug was reported by Heinrich.)

Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Rebase patch.
Remove unused fields from struct efi_loaded_image_obj.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>