net: phy: dp83848: Add PHY ID for TI version of DP83848C

After acquiring National Semiconductor, TI appears to have
changed the Vendor Model Number for the DP83848C PHYs,
add this new ID to supported IDs.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>