How to reduce smokey BBQ liquid flavor in a Mexican soup
Dilution is the solution to pollution.
There is no way to cover that smoke flavor.  But you can thin out the Mexican soup with some other bland soup and that might turn out good.  You could use tomato soup, or cheese soup or really any soup with flavors you think might be complemented by the Mexican soup.  I am thinking clam chowder with smoky Mexican soup might be pretty good.
That said, I think some liquid smoke flavor is just bad.  I never use it because I am scared of it.  If the problem with the Mexican soup is not just too much smoke flavor but bad smoke flavor, throw out the soup.  That bad smoke flavor comes out your pores after you eat it which is freaky.