LimeSDR-XTRX GNSS UART test never terminates on a read timeout #394

The port is configured with VMIN = 0 / VTIME = 10, so read() returns 0 after a one-second timeout with no data. The loop treats that as progress-free success:

for (int b = 0; b < bytesToRead;)
{
    int bread = read(tty_fd, inMessage + b, sizeof(16));
    if (bread < 0) { ... return OpStatus::Error; }
    b += bread;
}

A silent GNSS UART hangs the OEM test forever. Two more problems in the same block: sizeof(16) is 4, not the intended 16-byte chunk, and the open() of the uart node is never checked.