net: ethernet: ti: am65-cpsw: keep active if cpts enabled

Some K3 CPSW NUSS instances can lose context after PM runtime ON->OFF->ON
transition depending on integration (including all submodules: CPTS, MDIO,
etc), like J721E Main CPSW (CPSW9G).

In case CPTS is enabled it's initialized during probe and does not expect
to be reset. Hence, keep K3 CPSW active by forbidding PM runtime if CPTS is
enabled.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>