usb: dwc3: imx8mp: detect dwc3 core node via compatible string

New schema of usb controller DT-node should be named with prefix
"^usb(@.*)?", dt changed the node name, but missed counter part
change in driver, fix it by switching to use compatible string as
the dwc3 core compatible string keeps "snps,dwc3" in all dt.

Fixes: d1689cd ("arm64: dts: imx8mp: Use the correct name for child node "snps, dwc3"")
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Li Jun <jun.li@nxp.com>
Link: https://lore.kernel.org/r/1619765836-20387-1-git-send-email-jun.li@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Junlisuzhou

drivers/usb/dwc3/dwc3-imx8mp.c

@@ -165,7 +165,7 @@ static int dwc3_imx8mp_probe(struct platform_device *pdev)
 	if (err < 0)
 		goto disable_rpm;
 
-	dwc3_np = of_get_child_by_name(node, "dwc3");
+	dwc3_np = of_get_compatible_child(node, "snps,dwc3");
 	if (!dwc3_np) {
 		dev_err(dev, "failed to find dwc3 core child\n");
 		goto disable_rpm;