greybus: gpio: fix set-debounce request alignment

Fix alignment of the usec-field in the set-debounce request, which
should follow the which-field without any inserted padding.
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/gpio.c

@@ -116,7 +116,7 @@ struct gb_gpio_set_value_request {
 
 struct gb_gpio_set_debounce_request {
 	__u8	which;
-	__le16	usec;
+	__le16	usec __packed;
 };
 /* debounce response has no payload */