usb: ehci-ci: remove redundant PORTSC flag definitions

These definitions are unused, all boards that define portsc flags use
the equivalent PORT_* definitions instead.

Signed-off-by: Markus Niebel <Markus.Niebel@ew.tq-group.com>
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>