Fix powerControlDir creation failure error message

It had had a ": " separator that got lost in a previous edit.

Fixes: 41a49aa647a3c ("Use phosphor::logging instead of std::cerr")
Change-Id: I5221a461a43333623ce1cfb7f7ea2b900ecb50a5
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
diff --git a/power-control-x86/src/power_control.cpp b/power-control-x86/src/power_control.cpp
index 3646ca1..d6d8433 100644
--- a/power-control-x86/src/power_control.cpp
+++ b/power-control-x86/src/power_control.cpp
@@ -756,8 +756,8 @@
     {
         if (ec.value() != 0)
         {
-            std::string errMsg =
-                "failed to create " + powerControlDir.string() + ec.message();
+            std::string errMsg = "failed to create " +
+                                 powerControlDir.string() + ": " + ec.message();
             phosphor::logging::log<phosphor::logging::level::ERR>(
                 errMsg.c_str());
             return -1;