net/cxgb4: Fix referencing freed adapter

The adapter is freed before we check its flags. It was caused
by commit 144be3d9 ("net/cxgb4: Avoid disabling PCI device for
towice"). The problem was reported by Intel's "0-day" tool.

The patch fixes it to avoid reverting commit 144be3d9

.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>