mic_virtio: robust feature array size calculation

mic reads sizeof(vdev->features) bits from device, but in fact it stores
bits in local features variable. use sizeof(features) to make code
robust against future changes extending sizeof(vdev->features).
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/misc/mic/card/mic_virtio.c

@@ -76,8 +76,7 @@ static u32 mic_get_features(struct virtio_device *vdev)
 	u8 __iomem *in_features = mic_vq_features(desc);
 	int feature_len = ioread8(&desc->feature_len);
 
-	bits = min_t(unsigned, feature_len,
-		sizeof(vdev->features)) * 8;
+	bits = min_t(unsigned, feature_len, sizeof(features)) * 8;
 	for (i = 0; i < bits; i++)
 		if (ioread8(&in_features[i / 8]) & (BIT(i % 8)))
 			features |= BIT(i);