ARM: da8xx: remove con_id from USB clocks

There is only one clock each for "musb-da8xx" and "ohci-da8xx", so we
do not the the con_id. Removing them  will also prevent needing an
unnecessary device tree property when device tree bindings are added
for clocks.

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