arm: mach-k3: j7200: Add mcu_timer0 id to the dev list

mcu_timer0 is now used as the tick timer in u-boot, so this adds the
timer to the soc device list so it can be enabled via the k3 power
controller.

Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Reid Tonking <reidt@ti.com>