libxc: fix xc_dom_load_elf_symtab

libxc: fix xc_dom_load_elf_symtab

xc_dom_load_elf_symtab was incorrectly trying to perform the same
calculations already done in elf_parse_bsdsyms when load == 0 is used.
Instead of trying to repeat the calculations, just trust what
elf_parse_bsdsyms has already accounted for.

This also simplifies the code by allowing the non-load case to return
earlier.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>