objtool: Remove .fixup handling

The .fixup has gone the way of the Dodo, that test will always be
false.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101326.261496792@infradead.org