octeontx2-af: Add support for stripping STAG/CTAG

This works by shadowing existing UCAST MCAM entry
with a new one additionally matching either NPC_LT_LB_CTAG
or NPC_LT_LB_STAG. For this to fully work one needs to
send properly configured NIX_VTAG_CFG message afterwards i.e with
strip and capture enabled and type set to 0.

On receiving tagged packet NIX will remove outer VLAN and capture
TCI in NIX_RX_PARSE_S.

Also simplified RX Vtag configuration flow
With this setting STRIP/CAPTURE VTAG actions separately would be
possible. Following combinations are possible: STRIP,
STRIP and CAPTURE, CAPTURE or nothing (0 disables respective actions).

Signed-off-by: Tomasz Duszynski <tduszynski@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>