Telephony: Only one short sms can be read if long sms copied to CT card

According to 3GGP2 C.S0023 3.4.27, the maximum length of the message
is 255. But in java, byte cast to int, the result will be expanded when
byte value larger than 127.

To fix it, using 0xFF transfer byte to int type first.

CRs-Fixed: 960870

Change-Id: I8b2cc44db5a50ae9e3e289440ae0b19368512382