cxgb4: Add comment for calculate tx flits and sge length code

Add comment for tx filt and sge length calucaltion code, also remove
a hardcoded value

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