btrfs: use new block error code

This function is supposed to return blk_status_t error codes now but
there was a stray -ENOMEM left behind.

Fixes: 4e4cbee9 ("block: switch bios to blk_status_t")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/btrfs/compression.c

@@ -638,7 +638,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 							      __GFP_HIGHMEM);
 		if (!cb->compressed_pages[pg_index]) {
 			faili = pg_index - 1;
-			ret = -ENOMEM;
+			ret = BLK_STS_RESOURCE;
 			goto fail2;
 		}
 	}