usbhubd: gate port-indicator SetPortFeature on hub capability

SetPortFeature(PORT_INDICATOR) was issued unconditionally for every
connected+enabled port. QEMU's usb-hub does not advertise indicator
support and NAKs the request indefinitely; with no control-transfer
timeout the daemon hung before the post-enable debounce, so devices
behind the hub never attached. Gate on wHubCharacteristics bit 7
(HUB_CHAR_PORTIND, USB 2.0 Table 11-13), matching Linux hub_configure's
has_indicators check.

drivers/usb/usbhubd/src/main.rs

@@ -159,7 +159,7 @@ fn main() {
         .expect("Failed to find suitable configuration");
 
     // Read hub descriptor
-    let (ports, usb_3, b_pwr_on_2_pwr_good, w_hub_delay, device_removable) = if desc.major_version() >= 3 {
+    let (ports, usb_3, b_pwr_on_2_pwr_good, w_hub_delay, device_removable, hub_characteristics) = if desc.major_version() >= 3 {
         let mut hub_desc = usb::HubDescriptorV3::default();
         handle
             .device_request(
@@ -179,6 +179,7 @@ fn main() {
             10u8,
             u16::from(hub_desc.delay),
             hub_desc.device_removable,
+            hub_desc.characteristics,
         )
     } else {
         let mut hub_desc = usb::HubDescriptorV2::default();
@@ -200,6 +201,7 @@ fn main() {
             // USB 2.0 device_removable bitmaps are variable-length and
             // not parsed (see hub.rs).
             0u16,
+            hub_desc.characteristics,
         )
     };
 
@@ -526,9 +528,14 @@ fn main() {
                 continue;
             }
 
-            // Linux 7.1: port indicator — set amber during reset/power-on,
-            // green when enabled.  Helps diagnose which port is active.
-            if snap.connected && snap.enabled && !snap.resetting {
+            // Gate on wHubCharacteristics bit 7 (HUB_CHAR_PORTIND, USB 2.0
+            // Table 11-13; Linux hub_configure's has_indicators): a hub that
+            // does not advertise indicator support may NAK this request
+            // indefinitely, and these control transfers have no timeout.
+            const HUB_CHAR_PORTIND: u16 = 0x0080;
+            if snap.connected && snap.enabled && !snap.resetting
+                && (hub_characteristics & HUB_CHAR_PORTIND) != 0
+            {
                 let _ = set_feature(&handle, port, usb::HubPortFeature::PortIndicator);
             }