Verify that Status variable is initialized.

submitted-by: jcarsey
reviewed-by: lgrosenb
reviewed-by: rhale

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11752 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Application/Shell/ShellEnvVar.c

@@ -154,6 +154,7 @@ GetEnvironmentVariableList(
       return (Status);
     }
   } else {
+    Status = EFI_SUCCESS;
     MaxVarSize = 16384;
   }