drivers: net: phy: aquantia: make it less verbose

The driver now unconditionally prints some information that's not
universally useful.  Replace printf with debug.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>