[U-Boot] [U-Boot,2/5] arm: Disable HVC PSCI calls by default

[Alexander Graf]

> All systems that are running on armv8 are running bare metal with firmware
> that implements PSCI running in EL3. That means we don't really need to expose
> the hypercall variants of them.
> 
> This patch leaves the code in, but makes the code explicit enough to have the
> compiler optimize it out. With this we don't need to worry about hvc vs smc
> calling convention when calling psci helper functions.
> 
> Signed-off-by: Alexander Graf <agraf at suse.de>
> Reviewed-by: Simon Glass <sjg at chromium.org>

Thanks, applied to