virtio-devices, block: Reject sector 0 discard/"write zeroes" requests

As well as rejecting writes to sector 0 in the case of raw files where
the user hasn't specified the image_type also reject virtio requests of
type discard and write_zeroes.

Signed-off-by: Rob Bradford <rbradford@meta.com>

virtio-devices/src/block.rs

@@ -263,6 +263,7 @@ impl BlockEpollHandler {
                 self.disk_nsectors.load(Ordering::SeqCst),
                 self.disk_image.as_mut(),
                 &self.serial,
+                self.disable_sector0_writes,
                 desc_chain.head_index() as u64,
             );