net: ti: cpsw-common: dont print error if ti_cm_get_macid() fails

It is quite common for ti_cm_get_macid() to fail on some of the
platforms it is invoked on. They include any platform where
mac address is not part of SoC register space.

On these platforms, mac address is read and populated in
device-tree by bootloader. An example is TI DA850.

Downgrade the severity of message to "information", so it does
not spam logs when 'quiet' boot is desired.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>