netlink: specs: tc: all actions are indexed arrays

Some TC filters have actions listed as indexed arrays of nests
and some as just nests. They are all indexed arrays, the handling
is common across filters.

Fixes: 2267672a ("doc/netlink/specs: Update the tc spec")
Link: https://patch.msgid.link/20250513221638.842532-1-kuba@kernel.org


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