ixgbe: fix registration order of driver and DCA nofitication

ixgbe_notify_dca cannot be called before driver registration
because it expects driver's klist_devices to be allocated and
initialized. While on it make sure debugfs files are removed
when registration fails.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jakub Kicinski <jakub.kicinski@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>