cxgb4: add support for offloading u32 filters

Add support for offloading u32 filter onto hardware.  Links are stored
in a jump table to perform necessary jumps to match TCP/UDP header.
When inserting rules in the linked bucket, the TCP/UDP match fields
in the corresponding entry of the jump table are appended to the filter
rule before insertion.  If a link is deleted, then all corresponding
filters associated with the link are also deleted.  Also enable
hardware tc offload as a supported feature.

Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>