btrfs: Be explicit about usage of min()

__btrfs_alloc_chunk contains code which boils down to:

    ndevs = min(ndevs, devs_max)

It's conditional upon devs_max not being 0. However, it cannot really be 0
since it's always set to either BTRFS_MAX_DEVS_SYS_CHUNK or
BTRFS_MAX_DEVS(fs_info->chunk_root). So eliminate the condition check and use
min explicitly. This has no functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -4769,8 +4769,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 		goto error;
 	}
 
-	if (devs_max && ndevs > devs_max)
-		ndevs = devs_max;
+	ndevs = min(ndevs, devs_max);
+
 	/*
 	 * the primary goal is to maximize the number of stripes, so use as many
 	 * devices as possible, even if the stripes are not maximum sized.