A 90 kg mover climbs a ladder to a height of 8 m in 32 s. Find the power rating of the mover. I solved by using P= mgh/t and came up with 220.5 watts. Is this correct or am I suppose to use P=w/t and not use gravity in the equation?

You will get the same answer either way, if w = work. Gravity enters into both calculations.