usb: gadget: Update config for SuperSpeedPlus

When a function is added to a configuration with usb_add_function(), the
configuration speed flags are updated. These flags indicate for which
speeds the configuration is valid for.

This patch adds a flag in the configuration for SuperSpeedPlus and
also updates this based on the existence of ssp_descriptors.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 11d2433..560330f 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -237,6 +237,8 @@
 		config->highspeed = true;
 	if (!config->superspeed && function->ss_descriptors)
 		config->superspeed = true;
+	if (!config->superspeed_plus && function->ssp_descriptors)
+		config->superspeed_plus = true;
 
 done:
 	if (value)