tools: blob_handler: delete return statement

Some build environments don't like explicit return statements from
methods returning void.  Remove this explicit return statement.

Change-Id: I6e65f90c65d2a858e14a9e1e0f0621f534dd085c
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/tools/blob_handler.cpp b/tools/blob_handler.cpp
index 781ee29..fd50c00 100644
--- a/tools/blob_handler.cpp
+++ b/tools/blob_handler.cpp
@@ -178,7 +178,6 @@
     std::copy(bytes.begin(), bytes.end(), std::back_inserter(payload));
 
     auto resp = sendIpmiPayload(BlobOEMCommands::bmcBlobWrite, payload);
-    return;
 }
 
 std::vector<std::string> BlobHandler::getBlobList()