DeviceUnpairWork: remove initialization of attempt
DeviceUnpairWork: remove initialization of attempt

Fixes: ca5a82e50536 ("DeviceUnpairWork: rewrite to by fully asynchronous")
Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server