Fix wrong reading the sms lengh of stored long sms in RUIM

According to 3GGP2 C.S0023 3.4.27, the maximum length of the message
is 255. For one byte casts to int, the result will be a negative value
when larger than 127, so must use 0xFF to transfer byte to int first.

Change-Id: Ia3d64cae91f12a46ef7a1602300b44209a353966
1 file changed