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>
diff --git a/drivers/staging/greybus/gpio.c b/drivers/staging/greybus/gpio.c
index 4af5050..458565a 100644
--- a/drivers/staging/greybus/gpio.c
+++ b/drivers/staging/greybus/gpio.c
@@ -116,7 +116,7 @@
 
 struct gb_gpio_set_debounce_request {
 	__u8	which;
-	__le16	usec;
+	__le16	usec __packed;
 };
 /* debounce response has no payload */