usb: chipidea: add CI_HDRC_TURN_VBUS_EARLY_ON for imx23

Until now the imx23 uses the imx27 platform flag. But the
imx23 needs the flag CI_HDRC_TURN_VBUS_EARLY_ON, too. So
fix this by adding a separate platform flag.

Suggested-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>