qlcnic: Fix return value in qlcnic_probe()

If the check of adapter fails and goes into the 'else' branch, the
return value 'err' should not still be zero.

Signed-off-by: Yongjian Xu <xuyongjiande@gmail.com>
Acked-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>