libelf: add `struct elf_binary*' parameter to elf_load_image

libelf: add `struct elf_binary*' parameter to elf_load_image

The meat of this function is going to need a copy of the elf pointer,
in forthcoming patches.

No functional change in this patch.

This is part of the fix to a security issue, XSA-55.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Chuck Anderson <chuck.anderson@oracle.com>