[rilmodem]pref RAT mode value mapping for RAT query for new UI

Need correct mapping in case of PREF_NET_TYPE_GSM_WCDMA  in
response to RIL_REQUEST_GET_PREFERRED_NETWORK_TYPE

Signed-off-by: Petri Takalokastari <petri.takalokastari@oss.tieto.com>
Merge pull request #62 from ptakalok/master

[rilmodem]pref RAT mode value mapping for RAT query for new UI