ixgbevf: Test Rx status bits directly out of the descriptor

Instead of keeping a local copy of the status bits from the descriptor
we can just read them directly - this is accomplished with the addition
of ixgbevf_test_staterr().

In addition instead of doing a byteswap on the status bits value, we
can byteswap the constant values we are testing since that can be done
at compile time which should help to improve performance on big-endian
systems.

CC: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>