Apple can continue to sell the AT&T iPhone 4, iPhone 3GS, iPhone 3G, and the first- and second-generation 3G iPads in the U.S. after the Obama administration overturned an import ban on the devices, Bloomberg reports. The import ban, which was to start today, came about after the U.S. International Trade Commission ruled that Apple violated a Samsung standards-essential patent. However, U.S. Trade Representative Michael Froman said the ban was…