[DISC] Removal of openHAB specific MQTT discovery patch

[DigiH]

Removal of openHAB specific MQTT discovery patch "ohdisc", as it is no longer required with openHAB 4.3 and later, and with openHAB before 4.3 MQTT discovery never was fully implemented anyway.

Checklist:

• The pull request is done against the latest development branch
• Only one feature/fix was added per PR and the code change compiles without warnings
• I accept the DCO.

[1technophile]

You could also remove:

// Set the line below to true so as to have autodiscovery working with OpenHAB
#ifndef OpenHABDiscovery
#  define OpenHABDiscovery false
#endif

From config_mqttDiscovery.h

[DigiH]

You could also remove:

True, I missed that one. thanks. Done

[1technophile]

Thanks