ARM: dts: dra72-evm-revc: add phy impedance settings

The default impedance settings of the phy is not the optimal
value, due to this the second ethernet is not working. Fix it
with correct values which makes the second ethernet port to work.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>