ARM: dts: r7s72100: add usb clocks to device tree

This adds the USB0 and USB1 clocks to the device tree.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>