cxgb4: Add flag tc_flower_initialized

Add flag tc_flower_initialized to indicate the
completion if tc flower initialization.

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