fix(clang): fix bugprone-narrowing-conversions errors

Remove silent narrowing conversions.
Note in fdt_patch_mem since the conversion of fdt_max_size occurs
on the boundary between hafnium and third_party libaries we use a
cast to make the conversion explicit however the conversion itself
is not removed.

Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
Change-Id: I4ece5be0262ae06e3dc63e5970ec1a014956a43f
diff --git a/src/arch/aarch64/hypervisor/handler.c b/src/arch/aarch64/hypervisor/handler.c
index 147c711..fff1ea2 100644
--- a/src/arch/aarch64/hypervisor/handler.c
+++ b/src/arch/aarch64/hypervisor/handler.c
@@ -969,7 +969,7 @@
 #if SECURE_WORLD == 1
 	struct vcpu_locked current_locked;
 	struct vcpu *current_vcpu = current();
-	int ret;
+	int64_t ret;
 
 	if (plat_ffa_vm_managed_exit_supported(current_vcpu->vm)) {
 		/* Mask all interrupts */