[pvmfw] Move memory flush functions to vmbase

To facilitate reusing the memory management code in rialto later.

Bug: 284462758
Test: m pvmfw_img
Change-Id: I9a544c783ff322d4894f0b3d7e10c0643908d48f
diff --git a/pvmfw/src/main.rs b/pvmfw/src/main.rs
index 5108eb4..8d48098 100644
--- a/pvmfw/src/main.rs
+++ b/pvmfw/src/main.rs
@@ -40,7 +40,6 @@
 use crate::dice::PartialInputs;
 use crate::entry::RebootReason;
 use crate::fdt::modify_for_next_stage;
-use crate::helpers::flush;
 use crate::helpers::GUEST_PAGE_SIZE;
 use crate::instance::get_or_generate_instance_salt;
 use crate::memory::MEMORY;
@@ -55,6 +54,7 @@
 use pvmfw_avb::Capability;
 use pvmfw_avb::DebugLevel;
 use pvmfw_embedded_key::PUBLIC_KEY;
+use vmbase::memory::flush;
 
 const NEXT_BCC_SIZE: usize = GUEST_PAGE_SIZE;