ionic: remove support for mgmt device

We no longer support the mgmt device in the ionic driver,
so remove the device id and related code.

Fixes: b3f064e9 ("ionic: add support for device id 0x1004")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>