Kernel/USB: Add support for bulk transfers

Kernel/Bus/USB/USBTransfer.cpp

@@ -43,4 +43,13 @@ void Transfer::set_setup_packet(USBRequestData const& request)
     m_request = request;
 }
 
+ErrorOr<void> Transfer::write_buffer(u16 len, void* data)
+{
+    VERIFY(len <= m_data_buffer->size());
+    m_transfer_data_size = len;
+    memcpy(buffer().as_ptr(), data, len);
+
+    return {};
+}
+
 }