usb-conn-gpio devices are a subnode of the USB interface controller, which
needs to be populated.
This allows having a non-type-c connector providing dual-role.

Signed-off-by: Alexander Stein <redacted>
---
Greg, thank you for your review.

This was tested on an imx8mp based board (TQMa8MPxL) which uses devicetree.
Unfortunately I have no non-imx platform available to test this on.

devm_of_platform_populate() _will_ fail on non-OF builds, so do not call this
on non-OF enabled platforms.
AFAICS on OF-platforms this call will only fail upon memory allocation errors.
If there are no subnodes, this call will not fail. So existing platform should
work as before.

Changes in v3:
* Unregister role-switch upon populating OF tree error
* Do not call devm_of_platform_populate() on non-OF platforms

Changes in v2:
* Added missing variable declaration

 drivers/usb/dwc3/drd.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index d7f76835137f..1dcce7a04b41 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c

@@ -9,6 +9,7 @@
 
 #include <linux/extcon.h>
 #include <linux/of_graph.h>
+#include "linux/of_platform.h"