net: ethernet: am65-cpsw: Build am65-cpsw-qos only if required

Build am65-cpsw-qos only if CONFIG_TI_AM65_CPSW_TAS is enabled.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>