block/io: Comment out permission assertions

block/io: Comment out permission assertions

In case of block migration, there may be writes to BlockBackends that do
not have the write permission taken. Before this issue is fixed (which
is not going to happen in 2.9), we therefore cannot assert that this is
the case.

Suggested-by: Kevin Wolf <[email protected]>
Signed-off-by: Max Reitz <[email protected]>
Reviewed-by: Kevin Wolf <[email protected]>
Tested-by: Kevin Wolf <[email protected]>
Message-id: 20170411145050[email protected]
Tested-by: Laurent Vivier <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>