gobi_cromo_plugin: handle reported capability changes correctly

Network data capability changes were not being handled correctly
because the constructor parameter names were hiding the member
variables of the DataCapabilitiesArgs struct.  Rename the member
variables so that this hiding does not occur.

BUG=chrome-os-partner:4660
TEST=run cellular_Signal, grep for Cap: in /var/log/messages
TEST=notice that there are no longer illegal values

Change-Id: Ic9ea63e82bd2a4e84b18c8c5b0bd4cd776b0e69f
diff --git a/gobi_modem.h b/gobi_modem.h
index 347b04d..2970174 100644
--- a/gobi_modem.h
+++ b/gobi_modem.h
@@ -340,9 +340,9 @@
   static gboolean DormancyStatusCallback(gpointer data);
 
   struct DataCapabilitiesArgs : public CallbackArgs {
-    DataCapabilitiesArgs(BYTE num_data_caps, BYTE* data_caps)
-      : num_data_caps(num_data_caps) {
-      ULONG* dcp = reinterpret_cast<ULONG*>(data_caps);
+    DataCapabilitiesArgs(BYTE num_caps, BYTE* data)
+      : num_data_caps(num_caps) {
+      ULONG* dcp = reinterpret_cast<ULONG*>(data);
       if (num_data_caps > 12)
         num_data_caps = 12;
       for (int i = 0; i < num_data_caps; i++)