tools: put all host-side code into host_tool namespace

To avoid confusion and organize the code itself more cleanly, place the
host-side code into its own namespace.

Change-Id: I573eb0494eb59874adb1d1eadc502499e928e396
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/tools/lpc.hpp b/tools/lpc.hpp
index 4b53f26..913fc5d 100644
--- a/tools/lpc.hpp
+++ b/tools/lpc.hpp
@@ -3,6 +3,9 @@
 #include "blob_interface.hpp"
 #include "interface.hpp"
 
+namespace host_tool
+{
+
 class LpcDataHandler : public DataInterface
 {
   public:
@@ -19,3 +22,5 @@
     blobs::FirmwareBlobHandler::UpdateFlags flags =
         blobs::FirmwareBlobHandler::UpdateFlags::lpc;
 };
+
+} // namespace host_tool