cxgb4i : Fix -Wmaybe-uninitialized warning.

Identified by kbuild test robot. csk family is always set to be AF_INET or
AF_INET6, so skb will always be initialized to some value but there is no harm
in silencing the warning anyways.

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Fixes : f42bb57c

 ('cxgb4i : Fix -Wunused-function warning')
Signed-off-by: David S. Miller <davem@davemloft.net>