usb: chipidea: prevent endless loop registering platform_devices when probe fails

Commit 40dcd0e8

 ("usb: chipidea: add PTW, PTS and STS handling") introduced
the following code to the ci_hdrc_probe() function:

+       if (!dev->of_node && dev->parent)
+               dev->of_node = dev->parent->of_node;

This inadvertently associates the ci_hdrc device with the ci_hdrc_imx
driver (which created the ci_hdrc device in the first place).

This results in ci_hdrc_imx_probe() being run for the ci_hdrc device
if ci_hdrc_probe() fails for some reason.
ci_hdrc_imx_probe() will happily create a new ci_hdrc platform_device
whose probing will likewise fail and trigger a new invocation of
ci_hdrc_imx_probe() ... ad nauseam.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Reviewed-and-tested-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>