Revert "net/phy: Add Vitesse 8641 phy ID"

This reverts commit 1298267b.

That commit claim that the Vitesse VSC8641 is compatible with Vitesse
82xx. But this is not true. It seems that all the registers used
in Vitesse phy driver are not compatible between 8641 and 82xx.
It does cause malfunction of the Ethernet on p1010rdb-pa board.
So we definitely need a rework in order to support the 8641 phy
in this driver.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>