[Pod] Simplify temperature reading data shape

[taesungh]

Following from #37/#47 and #55/#64, we made LimTemperature::read_lim_temps return a 4-tuple of temperature values, but in the FSM, we reshape that into a fixed-size array [f32; 4] to combine with a second set of measurements. The 4-tuple is initially produced from using array::map on another fixed-size array, so we could simply return that shape instead of unnecessarily reshaping twice.