bcachefs: fix the display format for show-super

bcachefs: fix the display format for show-super

There are three keys displayed in non-uniform format.
Let's fix them.

[Before]
```
Label:	testbcachefs
Version:	1.9: (unknown version)
Version upgrade complete:	0.0: (unknown version)
```

[After]
```
Label:					testbcachefs
Version:				1.9: (unknown version)
Version upgrade complete:		0.0: (unknown version)
```

Fixes: 7423330e30ab ("bcachefs: prt_printf() now respects \r\n\t")
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>