According to the ARM DEN0028A spec, hypervisor ID(VMID) should be stored
in x7 (or w7). This patch gets this value from the context and passes it
to Trusty. In order to do so, introduce new macros to pass five to eight
parameters to the Trusted OS.

Change-Id: I101cf45d0712e1e880466b2274f9a48af755c9fa
Signed-off-by: Anthony Zhou <anzhou@nvidia.com>
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>