Kernel/USB: Add configuration descriptor accessor

Author: https://github.com/Quaker762
Commit: 9002e837d3
Pull-request: https://github.com/SerenityOS/serenity/pull/14134
Reviewed-by: https://github.com/b14ckcat
Reviewed-by: https://github.com/linusg

Kernel/Bus/USB/USBDevice.h

@@ -49,6 +49,8 @@ public:
 
     ErrorOr<size_t> control_transfer(u8 request_type, u8 request, u16 value, u16 index, u16 length, void* data);
 
+    Vector<USBConfiguration> const& configurations() const { return m_configurations; }
+
 protected:
     Device(NonnullRefPtr<USBController> controller, u8 address, u8 port, DeviceSpeed speed, NonnullOwnPtr<Pipe> default_pipe);