cxgb4: increase max tx rate limit to 100 Gbps

T6 cards can support up to 100 G speeds. So, increase
max programmable tx rate limit to 100 Gbps.

Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>