netipmid: use std::shared_ptr instead of weak_ptr/lock

All of the instances of getSession and startSession were assigning the
result to a local shared_ptr via lock on the weak_ptr. It doesn't make
sense to demote the shared_ptr (from the sessionsMap) to a weak_ptr via
the return, only to promote to a shared_ptr again via lock.

Tested-by: running ipmitool -H a.b.c.d -P 0penBmc -I lanplus mc info
           Sessions start and stop, same as before.

Change-Id: Ic10779285891d73ee51115f16ed0000b38d1c52a
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/command/open_session.cpp b/command/open_session.cpp
index b41eefa..b48b7e9 100644
--- a/command/open_session.cpp
+++ b/command/open_session.cpp
@@ -50,16 +50,15 @@
     {
         // Start an IPMI session
         session =
-            (std::get<session::Manager&>(singletonPool)
-                 .startSession(
-                     endian::from_ipmi<>(request->remoteConsoleSessionID),
-                     static_cast<session::Privilege>(request->maxPrivLevel),
-                     static_cast<cipher::rakp_auth::Algorithms>(
-                         request->authAlgo),
-                     static_cast<cipher::integrity::Algorithms>(
-                         request->intAlgo),
-                     static_cast<cipher::crypt::Algorithms>(request->confAlgo)))
-                .lock();
+            std::get<session::Manager&>(singletonPool)
+                .startSession(
+                    endian::from_ipmi<>(request->remoteConsoleSessionID),
+                    static_cast<session::Privilege>(request->maxPrivLevel),
+                    static_cast<cipher::rakp_auth::Algorithms>(
+                        request->authAlgo),
+                    static_cast<cipher::integrity::Algorithms>(
+                        request->intAlgo),
+                    static_cast<cipher::crypt::Algorithms>(request->confAlgo));
     }
     catch (std::exception& e)
     {