arm64: dts: Add ARM PL022 SPI DT nodes for NS2

We have two ARM PL022 SPI instances in NS2 SoC. On NS2 SVK,
one of the ARM PL022 SPI host has Silabs si3226x slic connected
to chip-select #0 whereas second ARM PL022 SPI host has Atmel
AT25 EEPROM connected to chip-select #0.

This patch adds ARM PL022, Silabs si3226x, and Atmel AT25
DT nodes in NS2 DT and NS2 SVK DT respectively.

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>