ARM: dts: at91: sam9x60: Add missing flexcom definitions

Added the missing flexcom functions for all the flexcom nodes.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
[durai.manickamkr@microchip.com: added missing UART compatibles]
Signed-off-by: Durai Manickam KR <durai.manickamkr@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230207110651.197268-7-durai.manickamkr@microchip.com