Please add --min-iops --min-lat support for 2d graph

[nakadachi]

Please review my suggestion to change this function.
def scale_2dgraph_yaxis(settings, item, rw, maximum):

factordict = {"iops": 1.05, "lat": 1.25, "bw": 1.5, "slat": 1.25, "clat": 1.25 }

max_y = maximum["total"][item["type"]] * factordict[item["type"]]
min_y = 0 // The default min is 0.

if settings[f"max_{item['type']}"]:
    max_y = settings[f"max_{item['type']}"]
if settings[f"min_{item['type']}"]:                // Support --min-iops and --min-lat for 2D graph
    min_y = settings[f"min_{item['type']}"]

return (min_y, max_y)