ARM: dts: add DT for lan966 SoC and 2-port board pcb8291

This patch adds basic DT for Microchip lan966x SoC and associated board
pcb8291(2-port EVB). Adds peripherals required to allow booting: Interrupt
Controller, Clock, Generic ARMv7 Timers, Synopsys Timer, Flexcoms, GPIOs.
Also adds other peripherals like crypto(AES/SHA), DMA, Watchdog Timer, TRNG
and MCAN0.

Signed-off-by: Kavyasree Kotagiri <kavyasree.kotagiri@microchip.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20220221080858.14233-1-kavyasree.kotagiri@microchip.com