prefer prefix operators for non-primitive types

cppcheck recommended changes:
[src/FruDevice.cpp:639]
[src/EntityManager.cpp:349]
[src/EntityManager.cpp:502]

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Iaae360c4613d959094b7d05888fbc289484d17fc
diff --git a/src/EntityManager.cpp b/src/EntityManager.cpp
index 2f70483..b177119 100644
--- a/src/EntityManager.cpp
+++ b/src/EntityManager.cpp
@@ -346,7 +346,7 @@
                                    cmp_str>::const_iterator probeType;
 
         for (probeType = PROBE_TYPES.begin(); probeType != PROBE_TYPES.end();
-             probeType++)
+             ++probeType)
         {
             if (probe.find(probeType->first) != std::string::npos)
             {
@@ -499,7 +499,7 @@
             boost::container::flat_map<const char*, probe_type_codes,
                                        cmp_str>::const_iterator probeType;
             for (probeType = PROBE_TYPES.begin();
-                 probeType != PROBE_TYPES.end(); probeType++)
+                 probeType != PROBE_TYPES.end(); ++probeType)
             {
                 if (probe.find(probeType->first) != std::string::npos)
                 {
diff --git a/src/FruDevice.cpp b/src/FruDevice.cpp
index f7be420..4d5486d 100644
--- a/src/FruDevice.cpp
+++ b/src/FruDevice.cpp
@@ -723,7 +723,7 @@
 
     for (const std::string& area : FRU_AREAS)
     {
-        fruAreaOffsetField++;
+        ++fruAreaOffsetField;
         if (fruAreaOffsetField >= fruBytes.end())
         {
             return false;