MIPS: Lantiq: Falcon: fix asc clock definition

The clocks of the serial ports were not setup properly.

Signed-off-by: Thomas Langer <thomas.langer@lantiq.com>
Acked-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5659/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>