if you report interest income on schedule C it will be deemed self-employment income. (only interest income earned on trade accounts and notes receivable in the ordinary course of conducting a trade or business is subject to SE tax). There is no direct way around this in Turbotax. Proper entry of interest income on investments would be on schedule B using 1099-INT form. For the 1099-int payor - interest income from SMLLC XX-XXXXXXX
As an alternative that i don't recommend because Turbotax does not provide the IRS with any details of other income. report as other income and then as an other expense "interest income on line 5 transferred to schedule B -XXX"