dt-bindings: timer/ingenic,tcu: Add compatible strings for JZ4725B SoC

Add compatible strings for the PWM and watchdog IPs on the Ingenic
JZ4725B SoC.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>