ixgbe: Drop the _ADV of descriptor macros since all ixgbe descriptors are ADV

It doesn't make much sense to differentiate between advanced and legacy
descriptors when the only descriptors that ixgbe uses are advanced
descriptors.  As such we can drop the _ADV suffix since all ixgbe
descriptors are automatically advanced.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>