If you sold some of the stock acquired through dividend reinvestment along with stock acquired through the ESPP, then you do have to adjust the "ESPP" stocks' basis but you don't have to adjust the "dividend" stocks' basis.
Only shares actually acquired at a discount through an ESPP need any "special" treatment. The shares acquired via dividend reinvestment are plain-vanilla "stock", no different than a stock you'd buy through your stock broker.
When entering this information into TurboTax, break your sale into two parts- one for "ESPP" stock and one for "ordinary" stock (which is the portion of this sale that came from those reinvested dividends). You do not need to indicate that this ordinary stock originated from dividend reinvestment.
