don't set sock_available just to count it back to 0

src/TinyGsmClientBG96.h

@@ -544,12 +544,9 @@ protected:
       return 0;
     }
     size_t len = stream.readStringUntil('\n').toInt();
-    sockets[mux]->sock_available = len;
 
     for (size_t i=0; i<len; i++) {
       TINY_GSM_MODEM_STREAM_TO_MUX_FIFO_WITH_DOUBLE_TIMEOUT
-      sockets[mux]->sock_available--;
-      // ^^ One less character available after moving from modem's FIFO to our FIFO
     }
     waitResponse();
     DBG("### READ:", len, "from", mux);