phy: qcom: qmp-usb-legacy: fix NULL-deref on runtime suspend

Commit 413db06 ("phy: qcom-qmp-usb: clean up probe initialisation")
removed most users of the platform device driver data from the
qcom-qmp-usb driver, but mistakenly also removed the initialisation
despite the data still being used in the runtime PM callbacks. This bug
was later reproduced when the driver was copied to create the
qmp-usb-legacy driver.

Restore the driver data initialisation at probe to avoid a NULL-pointer
dereference on runtime suspend.

Apparently no one uses runtime PM, which currently needs to be enabled
manually through sysfs, with these drivers.

Fixes: e464a31 ("phy: qcom-qmp-usb: split off the legacy USB+dp_com support")
Cc: stable@vger.kernel.org	# 6.6
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240911115253.10920-3-johan+linaro@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: jhovold

drivers/phy/qualcomm/phy-qcom-qmp-usb-legacy.c

@@ -1248,6 +1248,7 @@ static int qmp_usb_legacy_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	qmp->dev = dev;
+	dev_set_drvdata(dev, qmp);
 
 	qmp->cfg = of_device_get_match_data(dev);
 	if (!qmp->cfg)