soc: bcm: brcmstb: Remove bare-metal ARM suspend/resume code

Since 2018 these platforms have supported entry via the ARM Trusted
Firmware using the standard PSCI SYSTEM_SUSPEND function calls. Remove
this legacy code.

Link: https://lore.kernel.org/r/20230224215249.239405-1-f.fainelli@gmail.com


Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>