ARM: dts: at91: sama7g5-ek: use blocks 0 and 1 of TCB0 as cs and ce

Use blocks 0 and 1 of TCB0 for clocksource and clockevent functionality.
PIT64B is already enabled on SAMA7G5 targets for this but TCB0 will be
used as a fallback only in case PIT64B will fail to probe.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20211020094656.3343242-4-claudiu.beznea@microchip.com