efi_loader: pass handle of loaded image

The handle of a loaded image is the value of the handle
member of the loaded image info object and not the
address of the loaded image info.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>