NVMeBasicContext: Allocate streambuf where it's used

Move it after the early-exits to avoid useless (de)allocation.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I31264eb01342bbf40ed88b23aadd34eae43957cd
diff --git a/src/NVMeBasicContext.cpp b/src/NVMeBasicContext.cpp
index 93802b9..e06a0a7 100644
--- a/src/NVMeBasicContext.cpp
+++ b/src/NVMeBasicContext.cpp
@@ -246,8 +246,6 @@
 
 void NVMeBasicContext::readAndProcessNVMeSensor()
 {
-    auto response = std::make_shared<boost::asio::streambuf>();
-
     if (sensors.empty())
     {
         return;
@@ -285,6 +283,7 @@
             }
         });
 
+    auto response = std::make_shared<boost::asio::streambuf>();
     response->prepare(1);
 
     /* Gather the response and dispatch for parsing */