prevent logspam from getObjectInterfaces

prevent logspam from "Failed to GetObject".

The function does not print anymore and its caller can print an error
if needed.

The error defaults to phosphor::logging::level::DEBUG since it's
looping over the associations.

Therefore, failure in one codepath does not constitute an error.

Tested: logspam is gone.

Change-Id: Ie800181ff80ed56846815ea377f347a784d49521
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/include/dbus-sdr/sdrutils.hpp b/include/dbus-sdr/sdrutils.hpp
index 7a001a6..b78e226 100644
--- a/include/dbus-sdr/sdrutils.hpp
+++ b/include/dbus-sdr/sdrutils.hpp
@@ -367,7 +367,7 @@
 
 namespace ipmi
 {
-std::map<std::string, std::vector<std::string>>
+std::optional<std::map<std::string, std::vector<std::string>>>
     getObjectInterfaces(const char* path);
 
 std::map<std::string, Value> getEntityManagerProperties(const char* path,