juno: Pull out some software components ...

On Juno, we don't need the following components so this patch
removes them of the images:
 - semihosting support;
 - FVP power controller support;
 - GICv3 support.

juno: Improve TZC-400 initialisation code ...

- Distinguish Juno specific from platform agnostic constants
 - Define constants for Juno TZC-400 NSAID

juno: Add a handler for 'ARM Architecture' SMC calls ...

Currently UEFI and Linux are using SMC calls in the 'ARM Architecture'
Owning Entity range so lets implement these to get things working.

UEFI probably doesn't actually need to issue the ID_PRESENCE and ID_UID
calls it does, and the device-tree used by Linux could specify the PSCI
identifiers instead. After those changes, this patch isn't required.

Signed-off-by: Jon Medhurst <tixy@linaro.org>

juno: Implement PM ops to power on CPUs ...

Signed-off-by: Jon Medhurst <tixy@linaro.org>

juno: Override platform_get_core_pos and platform_is_primary_cpu ...

Signed-off-by: Jon Medhurst <tixy@linaro.org>

juno: Update memory map and use generic MMU code ...

Signed-off-by: Jon Medhurst <tixy@linaro.org>

juno: Create as a trimmed copy of plat/fvp ...

Signed-off-by: Jon Medhurst <tixy@linaro.org>