Fix the IndexOutOfBoundsException when unpacking GSM 8-bit pdu

Some wap push messages contains the charactors which are not in the
GSM 7 bit Default Alphabet table and its extension table, it cause the
IndexOutOfBoundsException when unpacking GSM 8-bit encoded pdu.
Solution: Replace them with white space.

Change-Id: I273953341cffddc2269332eabc556e303ff81bec
1 file changed