Address review comments for IPMI transport functions

Call get bus interface instead of using extern.
Define the IPMI request parameters.
Use snprintf.
Initialize dbus variables at the beginning of the function.
diff --git a/transporthandler.h b/transporthandler.h
index 49b1d95..ce7842b 100644
--- a/transporthandler.h
+++ b/transporthandler.h
@@ -15,4 +15,13 @@
     IPMI_CC_PARM_NOT_SUPPORTED = 0x80,
 };
 
+// Parameters
+static const int LAN_PARM_INPROGRESS  = 0;
+static const int LAN_PARM_AUTHSUPPORT = 1;
+static const int LAN_PARM_AUTHENABLES = 2;
+static const int LAN_PARM_IP          = 3;
+static const int LAN_PARM_MAC         = 5;
+static const int LAN_PARM_SUBNET      = 6;
+static const int LAN_PARM_GATEWAY     = 12;
+
 #endif