Migrate secure payload dispatchers to new SMC terminology

Migrate secure payload dispatchers to new SMC terminology

Since Issue B (November 2016) of the SMC Calling Convention document
standard SMC calls are renamed to yielding SMC calls to help avoid
confusion with the standard service SMC range, which remains unchanged.

http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pd

A previous patch introduced a new define for yielding SMC call type.
This patch updates the secure payload dispatchers (except the TSPD) to
use this new define and also migrates the code to use the new
terminology.

Change-Id: I3d2437c04e3b21fdbd32019f55c066c87679a5bf
Signed-off-by: David Cunado <david.cunado@arm.com>