net/cxgbe: add devargs to control filtermode and filtermask

Apart from the 4-tuple (IP src/dst addresses and TCP/UDP src/dst
port addresses), there are only 40-bits available to match other
fields in packet headers. Not all combinations of packet header
fields can fit in the 40-bit tuple.

Currently, the combination of packet header fields to match are
configured via filterMode for LETCAM filters and filterMask for
HASH filters in firmware config files (t5/t6-config.txt). So, add
devargs to allow User to dynamically select the filterMode and
filterMask combination during runtime, without having to modify the
firmware config files and reflashing them onto the adapter. A table
of supported combinations is maintained by the driver to internally
translate the User specified devargs combination to hardware's internal
format before writing the requested combination to hardware

Signed-off-by: Karra Satwik <kaara.satwik@chelsio.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>