gsup: fix error log message

The error happened in auth info and not in PDP info

Change-Id: I37ac6b5d7d34ba2ab0f83bcc1701b86b1a245014
diff --git a/src/gsm/gsup.c b/src/gsm/gsup.c
index 4e09ac8..4e18ddb 100644
--- a/src/gsm/gsup.c
+++ b/src/gsm/gsup.c
@@ -266,7 +266,7 @@
 
 parse_error:
 	LOGP(DLGSUP, LOGL_ERROR,
-	     "GSUP IE type %d, length %zu invalid in PDP info\n", iei, value_len);
+	     "GSUP IE type %d, length %zu invalid in auth info\n", iei, value_len);
 
 	return -1;
 }