ixgbe: Add bit to mark service task initialization

There needs to be an indication when the service task has been
initialized. This is because register access prior to that time
can detect a removal and attempt to schedule the service task.
Adding the __IXGBE_SERVICE_INITED bit allows this to be checked
and if not set prevent the service task scheduling. By checking
for a removal right after initialization, the probe can be failed
at that point without getting the service task involved.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>