block: row: Fix crash when adding a new field in bio struct

When adding new field to struct bio there is a crash in the removed
code lines. This issue was introduced by commit
80a8f0f87bee18283e9ca0a8966ec97ad9f084e5  "block: row-iosched idling
triggered by readahead pages"

(Partly) reverting this patch till root cause is fixed (on FS level).