psci: Make the assembly code match the structure defined in C

[arichardson]

The output argument is a struct containing uintptr_t, so we should be storing capabilities there and not integers. Alternatively, the struct should be changed to always use ptraddr_t.

[jrtc27]

Noticed this before but IIRC nothing passes non-NULL for the 9th argument so in practice it's dead code (other than the load from the stack, which works due to endianness). Worth fixing though.

[jrtc27]

The struct probably should be register_t though to match the argument types until such time as PSCI gains a capability-aware interface (which changes almost nothing except for CPU_ON, IIRC)

[arichardson]

Fix has been merged.