tests/qtest/usb-hcd-ehci-test: Check for EHCI and UHCI HCDs before using them

The devices might not be available in the binary (e.g. when compiling
with "--without-default-devices"), so we have to check before we can
use them.

Message-Id: <20230525081016.1870364-5-thuth@redhat.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/usb-hcd-ehci-test.c

@@ -149,6 +149,11 @@ int main(int argc, char **argv)
 
     g_test_init(&argc, &argv, NULL);
 
+    if (!qtest_has_device("ich9-usb-ehci1") ||
+        !qtest_has_device("ich9-usb-uhci1")) {
+        return 0;
+    }
+
     qtest_add_func("/ehci/pci/uhci-port-1", pci_uhci_port_1);
     qtest_add_func("/ehci/pci/ehci-port-1", pci_ehci_port_1);
     qtest_add_func("/ehci/pci/ehci-config", pci_ehci_config);