Platform: OLPC: Avoid a warning if the EC didn't register yet

Just return EPROBE_DEFER, so that whoever attempted to use the EC call can
defer their work.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/olpc/olpc-ec.c

@@ -125,8 +125,11 @@ int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
 	struct olpc_ec_priv *ec = ec_priv;
 	struct ec_cmd_desc desc;
 
-	/* Ensure a driver and ec hook have been registered */
-	if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
+	/* Driver not yet registered. */
+	if (!ec_driver)
+		return -EPROBE_DEFER;
+
+	if (WARN_ON(!ec_driver->ec_cmd))
 		return -ENODEV;
 
 	if (!ec)