ixgbe: use e_dev_warn instead of netif_printk

Again, we should not be directly using netif_printk, as we have our own
error print routines that we generate. In addition, instead of using an
early return we can just use the else block of this one line if
statement.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>