cxgb4: Add debugfs options to dump the rss key, config for PF, VF, etc

Adds support to dump the rss table, rss_config, rss_key, rss_pf_config and
rss_vf_config

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