logging: switch to lg2

After switching to C++20, it is recommended to use `phosphor::lg2`
to format log, and the correct `CODE_LINE` and `CODE_FUNC` values
can be used in log tracking.

Tested: built phosphor-srvcfg-manager successfully and Unit Test
passes.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: Ib676a0d8082b0e3e72b51bd5115bf5b05599e6ec
diff --git a/src/main.cpp b/src/main.cpp
index 1d9ebed..5723de2 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -220,8 +220,8 @@
                          const std::vector<ListUnitsType>& listUnits) {
             if (ec)
             {
-                phosphor::logging::log<phosphor::logging::level::ERR>(
-                    "async_method_call error: ListUnits failed");
+                lg2::error("async_method_call error: ListUnits failed: {EC}",
+                           "EC", ec.value());
                 return;
             }
             handleListUnitsResponse(server, conn, ec, listUnits);
@@ -238,8 +238,8 @@
                          const std::variant<uint64_t>& value) {
             if (ec)
             {
-                phosphor::logging::log<phosphor::logging::level::ERR>(
-                    "async_method_call error: ListUnits failed");
+                lg2::error("async_method_call error: ListUnits failed: {EC}",
+                           "EC", ec.value());
                 return;
             }
             if (std::get<uint64_t>(value))
@@ -267,8 +267,9 @@
                     }
                     if (ec)
                     {
-                        phosphor::logging::log<phosphor::logging::level::ERR>(
-                            "service config mgr - init - async wait error.");
+                        lg2::error(
+                            "service config mgr - init - async wait error: {EC}",
+                            "EC", ec.value());
                         return;
                     }
                     checkAndInit(server, conn);