cxgb4: handle 4-tuple PEDIT to NAT mode translation

cxgb4: handle 4-tuple PEDIT to NAT mode translation

BugLink: https://bugs.launchpad.net/bugs/1902115
[ Upstream commit 2ef813b8f405db3f72202b6fcae40a628ab80a53 ]

The 4-tuple NAT offload via PEDIT always overwrites all the 4-tuple
fields even if they had not been explicitly enabled. If any fields in
the 4-tuple are not enabled, then the hardware overwrites the
disabled fields with zeros, instead of ignoring them.

So, add a parser that can translate the enabled 4-tuple PEDIT fields
to one of the NAT mode combinations supported by the hardware and
hence avoid overwriting disabled fields to 0. Any rule with
unsupported NAT mode combination is rejected.

Signed-off-by: Herat Ramani <herat@chelsio.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>