input: Write a python function to calculate the minimum steps to make all elements of an array equal by decrementing the values. 
  assert min_steps([1, 2, 3]) == 3
  assert min_steps([1, 1, 1]) == 0
  assert min_steps([5, 6, 8, 8, 5]) == 7
output: def min_steps(arr):
      min_val = min(arr)
      return sum(x - min_val for x in arr)