greybus: loopback: add reserved fields to track firmware latencies

The greybus specification has been extended to include two new reserved
fields, which the implementation is using to track internal firmware
latencies. This change adds the appropriate fields to the corresponding
kernel header.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/greybus_protocols.h

@@ -958,6 +958,8 @@ struct gb_loopback_transfer_request {
 
 struct gb_loopback_transfer_response {
 	__le32	len;
+	__le32	reserved0;
+	__le32	reserved1;
 	__u8	data[0];
 } __packed;