greybus: gpio: Print expected/actual payload size on mismatch

Print (expected-payload-size actual-payload-size), when the size doesn't
match for requests received by the module. This gives more details
required for debugging the issue.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/gpio.c

@@ -366,7 +366,8 @@ static int gb_gpio_request_recv(u8 type, struct gb_operation *op)
 	request = op->request;
 
 	if (request->payload_size < sizeof(*event)) {
-		dev_err(ggc->chip.dev, "short event received\n");
+		dev_err(ggc->chip.dev, "short event received (%zu < %zu)\n",
+			request->payload_size, sizeof(*event));
 		return -EINVAL;
 	}