keepassx: restore nou2f

I could not find anything to confirm that keepassx supports hardware
keys.  And as mentioned by @rusty-snake[1]:

> The yubikey support in kpxc seems to be based on
> https://github.com/kylemanna/keepassx /
> keepassx/keepassx#52
> which was never merged. For me it looks like kpx never got official
> support for it.
>
> keepass seems to support hw keys (via plugin).

Also of note is the PR that added yubikey support to keepassxc:
keepassxreboot/keepassxc#127

This partially reverts commit 09ac1a7 ("keepass*: remove nou2f",
2022-02-05) / PR netblue30#4903.  See also commit 91b0417 ("keepass*: fix typo
in private-dev note", 2022-02-06).

Closes netblue30#4883.

[1] netblue30#4883 (comment)

etc/profile-a-l/keepassx.profile

@@ -32,16 +32,14 @@ nonewprivs
 noroot
 nosound
 notv
+nou2f
 novideo
 protocol unix
 seccomp
 shell none
 tracelog
 
 private-bin keepassx,keepassx2
-# Note: private-dev prevents the program from seeing new devices (such as
-# hardware keys) on /dev after it has already started; add "ignore private-dev"
-# to keepassxc.local if this is an issue (see #4883).
 private-dev
 private-etc alternatives,fonts,ld.so.cache,ld.so.preload,machine-id
 private-tmp