linker: cleanup of undefined state handling, which is really dead code

Given that _elf_lookup (and thus, _do_lookup) cannot possibly return an
undefined symbol (due to the check for SHN_UNDEF in _elf_lookup), there's
no need for spurious checks for SHN_UNDEF on its return value.

Conflicts:

	linker/linker.c

Change-Id: Ic73cf439924b45f72d4d9ba3f64a888c96cbbd9b
1 file changed