[VOL-2356]core log_level command line argument should take log level names not int value

- StringToLogLevel method returns two arguments.

Change-Id: I83d20d645fa63363e71265b163273414f14688a7
diff --git a/vendor/modules.txt b/vendor/modules.txt
index b3eb4a8..d52f5da 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -63,7 +63,7 @@
 github.com/mitchellh/go-homedir
 # github.com/mitchellh/mapstructure v1.1.2
 github.com/mitchellh/mapstructure
-# github.com/opencord/voltha-lib-go/v3 v3.0.10
+# github.com/opencord/voltha-lib-go/v3 v3.0.12
 github.com/opencord/voltha-lib-go/v3/pkg/adapters
 github.com/opencord/voltha-lib-go/v3/pkg/adapters/adapterif
 github.com/opencord/voltha-lib-go/v3/pkg/adapters/common