ixgbe: remove ixgbe_napi_add/del_all references

There were still some references to napi_add/del_all left after the dynamic
vector allocation patch.  This patch removes those references since the
ixgbe_napi_add/del_all calls are no longer needed as the napi struct is
added when the vector is created, and deleted when the vector is freed.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>