btrfs: remove deprecated mount option alloc_start

The mount option alloc_start has no effect since 0d0c71b317 ("btrfs:
obsolete and remove mount option alloc_start") which has details why
it's been deprecated. We can remove it.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2020-07-01 17:02:34 +02:00
commit d801e7a355