[MIPS] VPE: reimplement ELF loader.

Loading ELF binaries based on the section table is totally wrong.  This
still leaves the other fat bug of referencing symbols in an executable
unfixed, so people better don't run strip on their binaries ...

As added bonus the new loader is also 23 lines shorter.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>