ACK: [SRU][B,F,G] Fix incorrect printk format compile warning

[Andrea Righi]

On Tue, Nov 10, 2020 at 12:09:00PM -0800, Kamal Mostafa wrote:
> BugLink: https://bugs.launchpad.net/bugs/1902254
> 
> This mainline commit, recently backported to [B,F,G] for the bug above:
>     "btrfs: extent-tree: kill BUG_ON() in __btrfs_free_extent()"
> introduces a compile warning.
> 
> The warning has been fixed in mainline by:
>     cad69d139651 btrfs: tree-checker: fix incorrect printk format
> so let's pick up that fix too.
> 
> This patch is a trivial backport of that fix, which applies to [B,F,G].
> 
>  -Kamal

Trivial upstream fix, looks good to me.

Acked-by: Andrea Righi <andrea.righi at canonical.com>