arm: ls102xa: select USB PHY erratum's only if USB is enabled

The USB support is not by default enabled on all designs, so it does not
make seance to have USB specific erratum's enabled on such a designs.

On our internal Hitachi-Powergrids design not using the USB controller
there is a crash when accessing those specific memory locations selected
by the erratum flags.

Signed-off-by: Aleksandar Gerasimovski <aleksandar.gerasimovski@hitachi-powergrids.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>