erpt: fix multiple issues with automatic report cleanup (thanks @yellows8)

* Setting retrieval was performed before the call that used the setting.
* Call to detect number of files passed incomplete path and was guaranteed to fail.
* Call to delete reports passed incomplete path and was guaranteed to do nothing.

libraries/libstratosphere/include/stratosphere/erpt/srv/erpt_srv_types.hpp

@@ -21,6 +21,7 @@
 namespace ams::erpt::srv {
 
     constexpr inline const char ReportOnSdStoragePath[] = "ersd";
+    constexpr inline const char ReportOnSdStorageRootDirectoryPath[] = "ersd:/";
 
     constexpr inline const char ReportStoragePath[]             = "save";
     constexpr inline const char JournalFileName[]               = "save:/journal";