ionic: drop useless check of PCI driver data validity

The driver core will call to .remove callback only if .probe succeeded
and it will ensure that driver data has pointer to struct ionic.

There is no need to check it again.

Fixes: fbfb8031 ("ionic: Add hardware init and device commands")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>