Chipsets since revision AR5213A (0x59) have hardware counters for PHY errors
which we can read directly from the registers. Older hardware has to use the RX
descriptor status to get a count of PHY errors. This will be used in several
places in the ANI implementation, so a flag is useful.
Signed-off-by: Bruno Randolf <br1@einfach.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>