mips: dts: ingenic: Add TCU clock to x1000/x1830 tcu device node

This clock is a gate for the TCU hardware block on these SoCs, but
it wasn't included in the device tree since the ingenic-tcu driver
erroneously did not request it.

Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>