ice: Delete always true check of PF pointer

PF pointer is always valid when PCI core calls its .shutdown() and
.remove() callbacks. There is no need to check it again.

Fixes: 837f08fd ("ice: Add basic driver framework for Intel(R) E800 Series")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>