ArmPkg/Include: Add standard SMC function IDs for MM interface.

ArmPkg/Include: Add standard SMC function IDs for MM interface.

This patch adds a list of function IDs that fall under the standard
SMC range as defined in [1]

SMCs associated with Management Mode are in the range 0xC4000040 -
0xC400005f (64 bit) and 0x84000040 - 0x8400005f (32 bit).

The function(s) available to the normal world:
1. Request services from the secure MM environment using MM_COMMUNICATE.

It also defines MM return codes.

[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0060a/DEN0060A_ARM_MM_Interface_Specification.pdf.

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