net: phy: realtek: load driver for all PHYs with a Realtek OUI

Instead of listing every single PHYID, load the driver for every PHYID
with a Realtek OUI, independent of model number and revision.

This patch also improves two further aspects:
- constify realtek_tbl[]
- the mask should have been 0xffffffff instead of 0x001fffff so far,
  by masking out some bits a PHY from another vendor could have been
  matched

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>