ynl: support hex display_hint for integer

Some times it would be convenient to read the integer as hex, like
mask values.

Suggested-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20240327123130.1322921-2-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>