PEL: Fix some cppcheck warnings

This is the first of two commits to fix most of the cppcheck warnings in
the PEL code.  It doesn't fix all of them because some are false
positives and some are just suggestions.

It's broken up into two commits to make them smaller.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I75937797a6920611b136d600e9efd6c694e4209c
diff --git a/extensions/openpower-pels/repository.hpp b/extensions/openpower-pels/repository.hpp
index 2e8d2d6..5845afd 100644
--- a/extensions/openpower-pels/repository.hpp
+++ b/extensions/openpower-pels/repository.hpp
@@ -151,7 +151,7 @@
      *
      * @param[in] basePath - the base filesystem path for the repository
      */
-    Repository(const std::filesystem::path& basePath) :
+    explicit Repository(const std::filesystem::path& basePath) :
         Repository(basePath, getPELRepoSize(), getMaxNumPELs())
     {
     }
@@ -267,10 +267,7 @@
      */
     void subscribeToAdds(const std::string& name, AddCallback func)
     {
-        if (_addSubscriptions.find(name) == _addSubscriptions.end())
-        {
-            _addSubscriptions.emplace(name, func);
-        }
+        _addSubscriptions.emplace(name, func);
     }
 
     /**
@@ -298,10 +295,7 @@
      */
     void subscribeToDeletes(const std::string& name, DeleteCallback func)
     {
-        if (_deleteSubscriptions.find(name) == _deleteSubscriptions.end())
-        {
-            _deleteSubscriptions.emplace(name, func);
-        }
+        _deleteSubscriptions.emplace(name, func);
     }
 
     /**
@@ -566,7 +560,8 @@
      * @param[out] removedBMCLogIDs - The OpenBMC event log IDs of the
      *                                removed PELs.
      */
-    void removePELs(IsOverLimitFunc& isOverLimit, IsPELTypeFunc& isPELType,
+    void removePELs(const IsOverLimitFunc& isOverLimit,
+                    const IsPELTypeFunc& isPELType,
                     const std::vector<uint32_t>& idsWithHwIsoEntry,
                     std::vector<uint32_t>& removedBMCLogIDs);
     /**