refactor(ff-a): replace `plat_ffa_` prefix for public functions

Replace `plat_ffa_` prefix with `ffa_{file_name}_` prefix. Only do so
for public functions to avoid unnecessary churn (private functions are
renamed in the next commit).

Change-Id: I847c218f134a2519a45a3af1d6c4b953db9c1cbb
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
diff --git a/inc/hf/ffa/interrupts.h b/inc/hf/ffa/interrupts.h
index 398585d..a786114 100644
--- a/inc/hf/ffa/interrupts.h
+++ b/inc/hf/ffa/interrupts.h
@@ -30,7 +30,8 @@
 
 void ffa_interrupts_enable_virtual_interrupts(struct vcpu_locked current_locked,
 					      struct vm_locked vm_locked);
-
+void ffa_interrupts_mask(struct vcpu_locked receiver_vcpu_locked);
+void ffa_interrupts_unmask(struct vcpu *current);
 /**
  * Reconfigure the interrupt belonging to the current partition at runtime.
  */