pvmfw: Move aarch64 fn `jump_to_payload` to a separate module

Each architecture have its own boot protocole, so there is non generic way of implementing function `jump_to_payload(..)` in pvmfw for each platform. This commit move aarch64 specific logic to separate module hechaind `arch/aarch64` directories.

Bug: 354116267
Test: m pvmfw & boot payload

Change-Id: Ibac59fc1106c8f058fc35ff670d99e08567043cd
diff --git a/guest/pvmfw/src/arch/aarch64.rs b/guest/pvmfw/src/arch/aarch64.rs
index 8e7126d..171ba64 100644
--- a/guest/pvmfw/src/arch/aarch64.rs
+++ b/guest/pvmfw/src/arch/aarch64.rs
@@ -15,3 +15,4 @@
 //! aarch64 platform specific code
 
 pub mod exceptions;
+pub mod payload;