ARM: dts: brcmstb: add BCM7445 system PM DT nodes

Need the aon-ctrl, boot SRAM, and memory_controller descriptions.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
[florian: remove wake-timer, aon-pm-l2-intc duplicate]
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>