slimbus: qcom-ngd-ctrl: Avoid sending power requests without QMI

Attempting to send a power request during PM operations, when the QMI
handle isn't initialized results in a NULL pointer dereference. So check
if the QMI handle has been initialized before attempting to post the
power requests.

Fixes: 917809e2280b ("slimbus: ngd: Add qcom SLIMBus NGD driver")
Signed-off-by: Bjorn Andersson <[e-mail]>
Signed-off-by: Srinivas Kandagatla <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/slimbus/qcom-ngd-ctrl.c

···
 	struct qcom_slim_ngd_ctrl *ctrl = dev_get_drvdata(dev);
 	int ret = 0;
 
+	if (!ctrl->qmi.handle)
+		return 0;
+
 	if (ctrl->state >= QCOM_SLIM_NGD_CTRL_ASLEEP)
 		ret = qcom_slim_ngd_power_up(ctrl);
 	if (ret) {
···
 {
 	struct qcom_slim_ngd_ctrl *ctrl = dev_get_drvdata(dev);
 	int ret = 0;
+
+	if (!ctrl->qmi.handle)
+		return 0;
 
 	ret = qcom_slim_qmi_power_request(ctrl, false);
 	if (ret && ret != -EBUSY)