Fix two issues in Issue #80

Corrected the comment for the Get Channel Info command to
reflect the logic in the code. For issue two, corrected the
condition for returning the unspecifed error.

Fixes openbmc/phosphor-host-ipmid#80
diff --git a/ipmid.C b/ipmid.C
index 7354958..374ede2 100644
--- a/ipmid.C
+++ b/ipmid.C
@@ -273,7 +273,7 @@
     {
         fprintf(stderr,"ERROR:[0x%X] handling NetFn:[0x%X], Cmd:[0x%X]\n",r, netfn, cmd);
 
-        if(r == -1) {
+        if(r < 0) {
            response[0] = IPMI_CC_UNSPECIFIED_ERROR;
         }
     }