arm64: dts: Add ARM SP804 timer DT nodes for NS2

We have four ARM SP804 dual-mode timer instances in NS2 SoC
hence this patch adds appropriate DT nodes for NS2.

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