clk: at91: sam9x60: Register the required clocks for USB

Register into DM the clocks required to properly enable USB functionality
within the bootloader.

Signed-off-by: Sergiu Moga <sergiu.moga@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20221223123313.362676-3-sergiu.moga@microchip.com