objtool: Make handle_insn_ops() unconditional

Now that every instruction has a list of stack_ops; we can trivially
distinquish those instructions that do not have stack_ops, their list
is empty.

This means we can now call handle_insn_ops() unconditionally.

Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.795115188@infradead.org