octeontx2-af: npc: cn20k: Tear down default MCAM rules explicitly on free

octeontx2-af: npc: cn20k: Tear down default MCAM rules explicitly on free

npc_cn20k_dft_rules_free() used the NPC MCAM mbox "free all" path, which
does not match how cn20k tracks default-rule MCAM slots indexes.

Resolve the default-rule indices, then for each valid slot clear the bitmap
entry, drop the PF/VF map, disable the MCAM line, clear the target
function, and npc_cn20k_idx_free(). Remove any matching software mcam_rules
nodes. On hard failure from idx_free, WARN and stop so the box stays up for
analysis.

In npc_mcam_free_all_entries(), prefetch the same default-rule indices and,
on cn20k, skip bitmap clear and idx_free when the scanned entry is one of
those reserved defaults (they are released by npc_cn20k_dft_rules_free).

Fixes: 09d3b7a1403f ("octeontx2-af: npc: cn20k: Allocate default MCAM indexes")
Signed-off-by: Ratheesh Kannoth <rkannoth@marvell.com>
Link: https://patch.msgid.link/20260429022722.1110289-10-rkannoth@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>