libabis: ipaccess: use log instead of debug under errors in ipaccess_send()

This patch was suggested by Zecke.
diff --git a/openbsc/src/libabis/input/ipaccess.c b/openbsc/src/libabis/input/ipaccess.c
index ba641a8..cba03a0 100644
--- a/openbsc/src/libabis/input/ipaccess.c
+++ b/openbsc/src/libabis/input/ipaccess.c
@@ -200,7 +200,7 @@
 	if (ret < 0)
 		return ret;
 	if (ret < msglen) {
-		DEBUGP(DINP, "ipaccess_send: short write\n");
+		LOGP(DINP, LOGL_ERROR, "ipaccess_send: short write\n");
 		return -EIO;
 	}
 	return ret;