drivers/uart: stm32: fix a bug during transmission

If a transmission is made with poll_out and immediately after an other
transmission is made with interrupt api the transmission is locked.
We fix this behavior by clearing the tx_poll_stream_on flag during the
irq_tx_enable function

Signed-off-by: Julien D'ascenzio <julien.dascenzio@paratronic.fr>
1 file changed