Here are Tuesday's biggest calls on Wall Street: UBS upgrade Rivian to buy from neutral UBS said in its upgrade of the EV maker that it sees an attractive risk/reward." "We upgrade RIVN to Buy seeing an improved set-up, though our 12-month PT goes to $24 from $26." Read more about this call here. Bank of America reiterates Apple as neutral Bank of America said Apple Services is the "next leg of growth." "We rate Apple Neutral as we see risk-reward as balanced." Wells Fargo reiterates Amazon as overweight Wells said it sees "earnings power" ahead of the e-commerce giant's…