dt-bindings: microchip: atmel,at91rm9200-tcb: add sama5d2 compatible

The sama5d2 TC block TIMER_CLOCK1 is different from the at91sam9x5 one.
Instead of being MCK / 2, it is the TCB GCLK.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>