ArmPkg/Include: Add SVC function IDs for Management Mode.

ArmPkg/Include: Add SVC function IDs for Management Mode.

SVCs are in the range 0xC4000060 - 0xC400007f.
The functions available to the secure MM partition:
1. Signal completion of MM event handling.
2. Set/Get memory attributes for a memory region at runtime.
3. Get version number of secure partition manager.

Also, it defines memory attributes required for set/get operations.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Supreeth Venkatesh <supreeth.venkatesh@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>