btrfs: remove needless ASSERT check of orig_bio in end_compressed_bio_read

compressed_bio::orig_bio is always set in btrfs_submit_compressed_read
before any bio submission is performed. Since that function is always
called with a valid bio it renders the ASSERT unnecessary.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -244,7 +244,6 @@ static void end_compressed_bio_read(struct bio *bio)
 	 * Record the correct mirror_num in cb->orig_bio so that
 	 * read-repair can work properly.
 	 */
-	ASSERT(btrfs_io_bio(cb->orig_bio));
 	btrfs_io_bio(cb->orig_bio)->mirror_num = mirror;
 	cb->mirror_num = mirror;