dp83640: fix phy status frame event parsing

If two eternal time stamp events occur at nearly the same time, the
phyter will add an extra word into the status frame. This commit fixes
the parsing code to recognize and skip over the extra word.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>