PEL: Rename function that gets RO data path

It was just named after the message registry path, but soon other files
will be in that same directory so make it more generic.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I91117d685aec43f26b9fc6baa2955de3d1affde4
diff --git a/extensions/openpower-pels/paths.hpp b/extensions/openpower-pels/paths.hpp
index 91d8c5f..8d7a20f 100644
--- a/extensions/openpower-pels/paths.hpp
+++ b/extensions/openpower-pels/paths.hpp
@@ -17,8 +17,8 @@
 std::filesystem::path getPELRepoPath();
 
 /**
- * @brief Returns the path to the message registry JSON file
+ * @brief Returns the path to the read only data directory
  */
-std::filesystem::path getMessageRegistryPath();
+std::filesystem::path getPELReadOnlyDataPath();
 } // namespace pels
 } // namespace openpower