tools: ynl: use display hints for formatting of scalar attrs

Use display hints for formatting scalar attrs. This is specifically
useful for formatting IPv4 addresses carried typically as u32.

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20240626201234.2572964-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>