qed: Fix static checker warning.

qed: Fix static checker warning.

Orabug: 25477939

Smatch compains about qed_roce_ll2_tx() dereference
of the 'cdev' variable while testing its validity later.
As the validation checking is an over-kill [variable would always
be set], simply remove it.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: abd49676c707 ("qed: Add RoCE ll2 & GSI support")
Signed-off-by: Yuval Mintz <Yuval.Mintz@caviumnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit ce6b04ee8b112cc9d5ef41ba697a3ffabc630f42)
Signed-off-by: Brian Maly <brian.maly@oracle.com>