Missed packets should be counted as drops, not as both drops
and errors. Errors should be reserved for things like link level
crc errors.
ixgbe has always counted missed packets as drops, but it mishandled the missed packet
counters such that it only counting 1/8 as many drops/errors as it should.
'660099c985e8 ixgbe: Restore missed packet accounting', fixed that and made
us notice it.