fix(qemu): use plat ffa hypervisor module

This is for a better consistency of platforms using FF-A. The plat_ffa
macro determines the type of Partition Manager whether being the SPMC or
Hypervisor. Align qemu to use the hypervisor plat ffa module.

Change-Id: I51d59174e75f29835d12224372a85059edef2028
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/BUILD.gn b/BUILD.gn
index b5186a0..952a490 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -176,6 +176,7 @@
   max_cpus = 8
   max_vms = 16
   toolchain_args = {
+    plat_ffa = "//src/arch/aarch64/plat/ffa:hypervisor"
     pl011_base_address = "0x09000000"
   }
 }
@@ -193,6 +194,7 @@
   max_cpus = 8
   max_vms = 16
   toolchain_args = {
+    plat_ffa = "//src/arch/aarch64/plat/ffa:hypervisor"
     pl011_base_address = "0x09000000"
     enable_vhe = "1"
   }