blkfront: fix sector/offset calculations in new BLOCK interface

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Remove commented-out dead code

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Update CHANGES

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Regenerate OASIS

Signed-off-by: David Scott <dave.scott@eu.citrix.com>