ixgb: Remove unnecessary defines, use pr_debug

Use the current logging styles.

Remove unnecessary _DEBUG_DRIVER_ and PFX, use pr_debug.
Coalesce format.

Signed-off-by: Joe Perches <joe@perches.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>