usb: gadget: f_serial: add suspend resume callbacks

Add suspend resume callbacks to notify u_serial of the bus suspend/resume
state.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/gadget/function/f_serial.c

@@ -348,6 +348,20 @@ static void gser_unbind(struct usb_configuration *c, struct usb_function *f)
 	usb_free_all_descriptors(f);
 }
 
+static void gser_resume(struct usb_function *f)
+{
+	struct f_gser *gser = func_to_gser(f);
+
+	gserial_resume(&gser->port);
+}
+
+static void gser_suspend(struct usb_function *f)
+{
+	struct f_gser *gser = func_to_gser(f);
+
+	gserial_suspend(&gser->port);
+}
+
 static struct usb_function *gser_alloc(struct usb_function_instance *fi)
 {
 	struct f_gser	*gser;
@@ -369,6 +383,8 @@ static struct usb_function *gser_alloc(struct usb_function_instance *fi)
 	gser->port.func.set_alt = gser_set_alt;
 	gser->port.func.disable = gser_disable;
 	gser->port.func.free_func = gser_free;
+	gser->port.func.resume = gser_resume;
+	gser->port.func.suspend = gser_suspend;
 
 	return &gser->port.func;
 }