Make LLDP-MED class optional

[Gruni22]

Sadly my switches ignore LLDP packages if they contain LLDP-MED information.
This is transmitted automatically when M x switch is added.
Simplest solution would be to make the LLDP class optional by adding an option.
-M x would also override -i

-M class
               Enable  emission  of  LLDP-MED frame. Depending on the selected class, the standard defines which
               set of TLV should be transmitted. See section 10.2.1. Some  devices  may  be  strict  about  this
               aspect. The class should be one of the following value:
               1     Generic Endpoint (Class I)
               2     Media  Endpoint  (Class  II).  In  this  case, the standard requires to define at least one
                     network policy through lldpcli.
               3     Communication Device Endpoints (Class III). In this case, the standard requires  to  define
                     at least one network policy through lldpcli.
               4     Network Connectivity Device

- i      Disable LLDP-MED inventory TLV transmission.  lldpd will still receive (and publish using SNMP if
               enabled) those LLDP-MED TLV but will not send them. Use this option if you don't want to transmit
               sensible information like serial numbers.