qcow2: Update handle_alloc() to support L2 slices

qcow2: Update handle_alloc() to support L2 slices

handle_alloc() loads an L2 table and limits the number of checked
clusters to the amount that fits inside that table. Since we'll be
loading L2 slices instead of full tables we need to update that limit.

Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.

Signed-off-by: Alberto Garcia <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Reviewed-by: Max Reitz <[email protected]>
Message-id: b243299c7136f7014c5af51665431ddbf5e99afd.1517840877[email protected]
Signed-off-by: Max Reitz <[email protected]>