icE1usb fw: Ensure alignement of the structure for the usb_data_write

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: Id80468ef95bb908cf34b6eeca04c83f1285fd2f5
diff --git a/firmware/ice40-riscv/icE1usb/usb_gps.c b/firmware/ice40-riscv/icE1usb/usb_gps.c
index ad893a5..0fe5c98 100644
--- a/firmware/ice40-riscv/icE1usb/usb_gps.c
+++ b/firmware/ice40-riscv/icE1usb/usb_gps.c
@@ -138,7 +138,7 @@
 	{
 		/* Default request */
 			/* Put as static to work around gcc aliasing bug ... */
-		static struct usb_cdc_notif_serial_state notif = {
+		static struct usb_cdc_notif_serial_state __attribute__((aligned(4))) notif = {
 			.hdr = {
 				.bmRequestType = USB_REQ_READ | USB_REQ_TYPE_CLASS | USB_REQ_RCPT_INTF,
 				.bRequest      = USB_NOTIF_CDC_SERIAL_STATE,