devlink: Fix TP_STRUCT_entry in trace of devlink health report

Fix a bug in trace point definition for devlink health report, as
TP_STRUCT_entry of reporter_name should get reporter_name and not msg.

Note no fixes tag as this is a harmless bug as both reporter_name and
msg are strings and TP_fast_assign for this entry is correct.

Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>