migration: Remove unused migrate_zero_blocks

migrate_zero_blocks is unused since
  eef0bae3a7 ("migration: Remove block migration")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240919134626.166183-3-dave@treblig.org
Signed-off-by: Peter Xu <peterx@redhat.com>
2 files changed