NFC: Workaround nfcpy message debug exception

NFC: Workaround nfcpy message debug exception

The current nfcpy version does not support new WSC connection handover
message format and the handover server fails to process the request due
to a debug print. As a temporary workaround, override
HandoverServer::_process_request() with a version that avoids pretty()
print of the handover messages. This can be removed once nfcpy has been
updated to support the new format.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>