objtool: Fix broken error handling in read_symbols()

objtool: Fix broken error handling in read_symbols()

The free(sym) call in the read_symbols() error path is fundamentally
broken: 'sym' doesn't point to any allocated block.  If triggered,
things would go from bad to worse.

Remove the free() and simplify the error paths.  Freeing memory isn't
necessary here anyway, these are fatal errors which lead to an immediate
exit().

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>