gitignore: ignore more generated files

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/kernel/.gitignore b/kernel/.gitignore
new file mode 100644
index 0000000..f2ab700
--- /dev/null
+++ b/kernel/.gitignore
@@ -0,0 +1,5 @@
+#
+# Generated files
+#
+config_data.h
+config_data.gz