usb: tcpm: fix inverted poll condition in tcpm_pd_transmit()

The read_poll_timeout() macro breaks out of its loop when the condition
evaluates to true. The current code uses "!tx_complete" as the
condition, which means it exits immediately when tx_complete is false
(i.e., transmission has NOT completed yet), rather than waiting for
completion.

Fix the condition to "tx_complete" so that the poll loop waits until
the TCPC signals transmission success/failure/discard before
proceeding.

Without this fix, tcpm_pd_transmit() returns before the TCPC has
finished transmitting, causing the PD state machine to proceed with
stale tx_status values.

Fixes: 1db4c0ac77 ("usb: tcpm: add core framework")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>

drivers/usb/tcpm/tcpm.c

@@ -207,7 +207,7 @@ static int tcpm_pd_transmit(struct udevice *dev,
 	 */
 	timeout_us *= 5;
 	ret = read_poll_timeout(tcpm_transmit_helper, tx_complete,
-				!tx_complete, false, timeout_us, dev);
+				tx_complete, false, timeout_us, dev);
 	if (ret < 0) {
 		dev_err(dev, "TCPM: PD transmit data failed: %d\n", ret);
 		return ret;