python.d/sensors: Increase voltage limits 127 -> 400 (#15905)

* Fix a limit that caused my properly functioning PMBus power supply sensor to be skipped as it reported 208VAC. * The 400V limit was pulled from the Open Compute Project M-CRPS specification v1.0 Section 5.1.3.2[0] which defines a power supply input voltage as 380VDC and specifies a Vmax of 400VDC. * Also decrease the lower limit to -400VDC as some telecom power supplies may report negative voltage, most notable is -48VDC and expect more could as well.