Fixed a typo in setting the V.27ter bit rate for T.38 gateway

libs/spandsp/src/t38_gateway.c

@@ -535,7 +535,7 @@ static int set_next_tx_type(t38_gateway_state_t *s)
             t->tx_bit_rate = 2400;
             break;
         case T38_IND_V27TER_4800_TRAINING:
-            t->tx_bit_rate = 2400;
+            t->tx_bit_rate = 4800;
             break;
         }
         /*endswitch*/