CDMA WDP datagram handling was refactored to use the same method
that handles concatenated SMS messages. WDP datagram sequence numbers
start at 0, but GSM/CDMA concatenated sequence numbers start at 1.
Changed SMSDispatcher.processMessagePart() to count from 0 when
handling WDP datagrams.
Also changed CdmaSMSDispatcher.processCdmaWapPdu() to correctly
decode segment numbers > 127 (signed byte conversion bug)
and to reject PDUs with an out-of-range segment number (invalid
ranges are already rejected for regular concatenated messages).
Bug: 5433331
Change-Id: I25c9567769de8edca789c0d1707d4916a4c46885