feat: allow an endpoint to specify optional timeout with FFA_YIELD

An endpoint can yield execution back to the VM that allocated it CPU
cycles rather than busy waiting (such as for an IO operation to
 complete). FF-A v1.2 spec allows the endpoint to specify an optional
64-bit timeout.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: I5481c5483f4edd71b95c15a11a118498c71e3fa1
diff --git a/inc/hf/arch/plat/ffa.h b/inc/hf/arch/plat/ffa.h
index b74df2c..1070a28 100644
--- a/inc/hf/arch/plat/ffa.h
+++ b/inc/hf/arch/plat/ffa.h
@@ -366,4 +366,6 @@
 				   struct vcpu *current, struct vcpu **next);
 
 struct ffa_value plat_ffa_yield_prepare(struct vcpu *current,
-					struct vcpu **next);
+					struct vcpu **next,
+					uint32_t timeout_low,
+					uint32_t timeout_high);