USB: ohci: da8xx: remove clk con_id

The ohci-da8xx device only has one clock, so a con_id is not needed, so
remove it. This way we don't have to add an unnecessary property to the
device tree bindings for the clock.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>