The rollover from your 401k to an IRA does not affect your IRA contribution limits. A rollover is not the same thing as a contribution.
You can still make a contribution to either a Traditional IRA or a Roth IRA based on the qualifications for the contribution. In order to reduce your AGI, you need to be able to make a deductible contribution to a Traditional IRA.
TurboTax will consider your income, filing status, age, retirement plans at work, and other factors to determine if you are eligible to make a deductible contribution to a Traditional IRA. Go through the IRA contribution section of your return and enter a possible contribution you would like to make. Then, pay close attention to the messages on screen to see what your limits may be.
The following TurboTax help article will give you instructions to get started: