ixgbe: Add function for testing status bits in Rx descriptor

This change adds a small function for testing Rx status bits in the
descriptor.  The advantage to this is that we can avoid unnecessary
byte swaps on big endian systems.

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>