iiod: iiod-serial: Fix memory leak
iiod: iiod-serial: Fix memory leak

In the function start_serial_daemon, the "dev" variable was never freed
when the thread was successfully created.

Signed-off-by: Paul Cercueil <a027184a55211cd23e3f3094f1fdc728df5e0500@crapouillou.net>

analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio