devlink: define enum for attr types of dynamic attributes

Devlink param and health reporter fmsg use attributes with dynamic type
which is determined according to a different type. Currently used values
are NLA_*. The problem is, they are not part of UAPI. They may change
which would cause a break.

To make this future safe, introduce a enum that shadows NLA_* values in
it and is part of UAPI.

Also, this allows to possibly carry types that are unrelated to NLA_*
values.

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20250505114513.53370-3-jiri@resnulli.us


Signed-off-by: Jakub Kicinski <kuba@kernel.org>